Kwikset 663SQT-UL.DS UL Rated ...
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Kwikset 663SQT-UL.DS UL Rated One Sided Turn Square Deadbolt with 2-3/8" Round Corner Latch and Dual RCS and 5303 Full Lip Strike

Kwikset 663SQT-UL.DS UL Rated One Sided Turn Square Deadbolt with 2-3/8" Round Corner Latch and Dual RCS and 5303 Full Lip Strike

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Model: 663SQT-26.UL.DS
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Kwikset 663SQT-UL.DS UL Rated One Sided Turn Square Deadbolt with 2-3/8" Round Corner Latch and Dual RCS and 5303 Full Lip Strike

The Kwikset 663SQT-UL.DS One-Sided Turn Square Deadbolt offers heavy-duty security and sleek modern style in one package. With a clean square design and UL fire rating, this one-sided deadbolt is ideal for residential or commercial applications that require strength, safety, and compliance. Featuring a 2-3/8" round corner latch, dual RCS (round corner square) strike plates, and a 5303 full lip strike, this deadbolt delivers maximum reinforcement, precise door alignment, and Kwikset’s trusted durability.

Key Features & Benefits

  • One-Sided Turn Deadbolt
    Operates with an interior thumb-turn only—no exterior keyway—for added security in private or restricted areas.

  • UL Rated for Safety
    Meets UL standards for fire resistance and durability, making it suitable for high-security residential or commercial use.

  • Modern Square Design
    Clean lines and a square rose plate complement contemporary décor and upgrade door hardware aesthetics.

  • 2-3/8" Round Corner Latch
    Sturdy latch ensures smooth operation and compatibility with standard doors.

  • Dual RCS Strike Plates
    Reinforced strike plates provide stronger frame support and reliable locking alignment.

  • 5303 Full Lip Strike Included
    Adds strength and ensures a secure, clean installation.

  • Kwikset Quality
    Backed by a brand known for innovation, durability, and trusted security.

Specifications

   
Product Type One-Sided Turn Deadbolt
Model Number 663SQT-UL.DS
Function Interior thumb-turn only (no key)
Design Style Square, modern design
Latch 2-3/8" Round Corner Latch
Strike Plates Dual RCS + 5303 Full Lip Strike
Rating UL Fire Rated
Door Thickness 1-3/8" to 1-3/4" standard
Application Residential or commercial security
Installation Easy DIY, screwdriver only

 

 

RESOURCES & DOWNLOADS

Kwikset KWI-663SQT-UL.DS UL Rated One Sided Turn Square Deadbolt with 2-3/8" Round Corner Latch and Dual RCS and 5303 Full Lip Strike

Manufacturer Resources

Product Specs

Product Group:
Mechanical Locks
Product Subgroup:
Deadbolts
Subcategory:
Deadbolts
Commercial/Residential:
Residential
Product Features:
Microban
Product Attribute:
Deadbolts
Product Type:
Deadbolts
Product Category:
Mechanical Locks
Department:
Door Hardware

Kwikset 663SQT-26.UL.DS – Frequently Asked Questions

1) Does the Kwikset 663SQT one-sided deadbolt have a keyway on the outside?
No exterior keyway at all. The 663SQT-UL.DS throws and retracts from an interior thumbturn only, and the outside face is blank. That is the point of a one-sided deadbolt: it secures a door from the inside (storage rooms, interior office doors, a door you never need to enter from the outside), and nobody can pick or bump what isn't there. The flip side is that once it's thrown, there is no way in from the outside, so don't put it on an opening anyone needs keyed access through.
2) I have a 2-3/4 inch backset door prep. Can I use this Kwikset one-sided deadbolt?
Not as supplied. The 663SQT comes with a 2-3/8 inch backset latch, so on a door already bored at 2-3/4 the bolt won't line up with the cross bore. Deadbolts sold with a 4-way adjustable backset handle either prep from one box, like the Brinks Mendocino E2402 square single cylinder or the Brinks Raleigh E2401 in round trim. Cal-Royal's ED500 also lists an adjustable backset. Those are keyed on the outside, though, so if you specifically need a blank exterior face, match the prep to 2-3/8 instead.
3) Which fire rated deadbolt should I use if the opening also needs a key cylinder?
The Kwikset 663SQT-UL.DS is UL fire rated but has no exterior keyway. For a keyed fire rated alternative, the Cal-Royal CRB800 is a Grade 1 heavy duty single cylinder deadbolt with a UL 3-hour fire rated latch, cylinder x thumbturn function. The Hager 3115 also carries a fire rating and is a Grade 2 cylinder x thumbturn deadbolt with a Schlage C keyway, covering 1-3/8 inch to 1-3/4 inch doors. For a Grade 1 keyed version, the Hager 3118 is fire rated with a Schlage C keyway and a 6-pin cylinder across the same thickness range.
4) What is a one-sided deadbolt equivalent to the Kwikset 663SQT if I need a different brand?
The Callan Model 205S is a one-sided half-bore deadbolt, Grade 3, and is the closest match in function to the Kwikset 663SQT-UL.DS, which operates from an interior thumb-turn only with no exterior keyway. Both put the turn on the secure side and leave the outside face without a cylinder, so the door opens only from inside. The Arrow E60 is the other non-keyed option: a Grade 2 exit deadlock with a blank plate on the outside and a thumbturn inside, covering a door thickness range of 1-3/8 inch to 1-3/4 inch, the same range the 663SQT-UL.DS is built for.
5) I need a square deadbolt but the door has to be keyed from outside. What should I order instead?
The Kwikset 663SQT-UL.DS is thumb-turn only, so if the opening needs outside key access, move to a keyed square-trim model. The Bravura 310SC Elite is a Grade 2 contemporary square deadbolt with cylinder x thumbturn function. The Brinks Mendocino Series E2402 is a contemporary square single cylinder deadbolt, also cylinder x thumbturn, with a 4-way adjustable backset. The Callan Model 200S is a Grade 3 single cylinder square trim deadbolt. All three keep the square aesthetic of the 663SQT-UL.DS while adding an exterior keyway.
6) Is the Baldwin Reserve Double Cylinder Contemporary Square Deadbolt the same thing as the Kwikset 663SQT?
No. They share the square trim look, but the Baldwin Reserve DC.CSD is a double cylinder deadbolt, meaning it takes a key on both faces and cannot be thrown or retracted by hand from inside. The Kwikset 663SQT-UL.DS is a one-sided turn deadbolt with an interior thumb-turn and no exterior keyway. If a code official or a life-safety review requires egress without a key, the double cylinder unit is not an interchangeable choice for the 663SQT-UL.DS.
7) I need to secure a thicker door than 1-3/4 inch. What deadbolt covers that?
The Kwikset 663SQT-UL.DS is built for 1-3/8 inch to 1-3/4 inch doors. For thicker stock, the Corbin Russwin DL3011 cylindrical deadlock covers 1-3/4 inch to 2-1/4 inch. The Deltana 7312KA2 double cylinder deadbolt covers 1-3/8 inch to 2 inch and is Grade 3. The Dexter DB1000 single cylinder runs to 1-7/8 inch. All of these are keyed rather than one-sided turn, so plan on a cylinder in the outside face.
8) We are keying a facility to an interchangeable core system. Which deadbolt works instead of the one-sided turn model?
The Kwikset 663SQT-UL.DS has no exterior cylinder, so it cannot be brought into a keying system at all. For openings that must be cored, the Arrow E61 26D IC is a Grade 2 single cylinder deadlock with SFIC prep supplied less core, covering 1-3/8 inch to 1-3/4 inch doors. The Deltana CL200LAIC is a Grade 2 single deadbolt with interchangeable core prep, non-cylinder, on a 2-3/4 inch backset. The Delaney LM Series 301702 is a Grade 1 single cylinder less core deadbolt in dull chrome US26D. A common pattern is the one-sided turn on interior and stairwell doors and a cored unit wherever a key is required.
9) What is the difference between the Kwikset 663SQT one-sided turn and a classroom function deadbolt?
They are different security models. The Kwikset 663SQT-UL.DS throws and retracts only from the interior thumb-turn and has no exterior keyway, so control sits with whoever is inside the room. A classroom function deadbolt such as the Falcon D111, Grade 1 heavy duty with an adjustable backset, or the Falcon D211, Grade 2 medium duty single cylinder, is operated by key from the corridor side. The Hager 3118 is another Grade 1 classroom deadbolt, using a Schlage C keyway with a 6-pin cylinder on 1-3/8 inch to 1-3/4 inch doors. Where a lockdown procedure requires staff to secure the door from inside without a key, the one-sided turn is the function that matches; where the key must stay with facilities, the classroom units do.
10) What comes in the box with the Kwikset 663SQT-UL.DS, and do I need to buy strikes separately?
Everything for the frame side is in the box. You get the deadbolt with square rose trim, the 2-3/8 inch round corner latch, dual RCS (round corner square) strike plates, and a 5303 full lip strike. The dual RCS plates cover both round corner and square corner frame preps, and the full lip strike is there for the frame where you want the extended lip to protect the jamb edge. Installation is screwdriver only.
11) What is the difference between a one-sided deadbolt and a single cylinder deadbolt?
A single cylinder deadbolt is keyed outside and thumbturn inside, so you can get in from either side. The Kwikset 663SQT is one-sided: thumbturn inside, blank plate outside, no key anywhere. Pick one-sided when the outside face never needs to open the door, or when you want no keyway exposed on a corridor or storefront side. Pick single cylinder when someone has to get in from outside. In the keyed direction there's the Arrow DBX61 (Grade 2 cylinder x thumbturn) or the Dexter DB1000 Series (Grade 1, 1-3/8 to 1-7/8 inch doors). For a commercial-style blank plate x thumbturn deadlock, the Arrow E60 is Grade 2 non-keyed for 1-3/8 to 1-3/4 inch doors.
12) I need a one-sided deadbolt but my door has only a half bore. What are my options?
The Kwikset 663SQT-UL.DS is a full-bore deadbolt: it uses a standard 2-3/8 inch backset cross bore straight through the door with a latch and strike. If your door is prepped with a half bore only, the Callan Model 205S is a Grade 3 one-sided half-bore deadbolt built for that prep. Check which prep you actually have before ordering, because the two are not interchangeable in the same hole.
13) Is there a square trim deadbolt that matches the Kwikset 663SQT but with a key outside?
If you're running square trim across a set of openings and need some of them keyed, square-face options include the Bravura 310SC Elite (Grade 2, cylinder x thumbturn), the Callan 200S (Grade 3, single cylinder square trim), the Brinks Mendocino E2402 (contemporary square, single cylinder), and for double cylinder the Baldwin Reserve Contemporary Square. Trim shape will read as a family; exact finish tones vary by brand, so pull one of each before committing a whole floor.
14) Can I use a mortise deadbolt in place of the Kwikset 663SQT square deadbolt?
Not without different door prep. The Kwikset 663SQT-UL.DS is a bored tubular deadbolt using a 2-3/8 inch round corner latch and a 5303 full lip strike. A mortise unit such as the Dormakaba D900 small case mortise deadbolt, cylinder x thumbturn, or the Emtek 2050 European mortise deadbolt with integrated roller latch in square trim, needs a mortise pocket cut into the door edge instead of a bore and latch face. The Arrow 460 in the same family is a mortise lock strike for latchbolt and deadbolt functions with a straight lip, sized for 1-3/4 inch doors, and is the frame side piece for that style of prep, not a replacement for the 5303 full lip strike.
15) What is the Grade 1 alternative if the spec calls for a higher grade deadbolt than the Kwikset 663SQT?
For openings written to Grade 1, the Accentra D111 is a Grade 1 single cylinder deadbolt with a 2-3/8 inch backset covering 1-3/8 inch to 1-3/4 inch doors, matching the door thickness the Kwikset 663SQT-UL.DS is built for and its 2-3/8 inch latch dimension. The Dexter DB1000 single cylinder is Grade 1 and spans 1-3/8 inch to 1-7/8 inch. The Falcon D111 is a Grade 1 heavy duty classroom deadbolt with an adjustable backset. All three are cylinder x thumbturn rather than one-sided, so the outside face carries a keyway.
16) What is the round trim version if the other doors in the building are round rose?
The Kwikset 663SQT-UL.DS carries square trim with a square rose plate. To match round rose hardware elsewhere in a building, the Bravura 310RC Elite is a Grade 2 contemporary round deadbolt and the Bravura 310B Elite is a Grade 2 traditional round deadbolt, both cylinder x thumbturn. The Brinks Raleigh Series E2401 is a transitional round single cylinder deadbolt with a 4-way adjustable backset, and the Baldwin Reserve DC.CRD is a double cylinder contemporary round deadbolt. Note that all four are keyed on the exterior, unlike the one-sided turn function of the 663SQT-UL.DS.
17) Is there a code or electronic deadbolt option instead of a thumb-turn only unit?
Yes, if the requirement is keyless entry from outside rather than the interior-only operation of the Kwikset 663SQT-UL.DS. The Codelocks CL200 is a surface deadbolt with key override, light duty. The Codelocks CL2200 is an electronic surface deadbolt in brushed steel, medium duty. The Delaney KP400 is a Grade 2 electronic deadbolt with a programmable remote. For access-controlled multifamily, the Dormakaba Nova-D is an RFID multihousing smart electronic deadbolt and the Saffire LX-D is an RFID electronic deadbolt with BLE and electronic lock override. These change how the door is credentialed, which the 663SQT-UL.DS does not address since it operates only from the secure side.
18) The thumbturn needs to be easy to operate for a resident with limited hand strength. What are my options?
The Kwikset 663SQT-UL.DS uses a square thumb-turn as its only operator. If the turn itself needs to be easier to grip and rotate, the Cal-Royal LSD is a Grade 3 single cylinder deadbolt with an ADA ergonomic thumbturn, covering 1-3/8 inch to 1-3/4 inch doors, the same thickness range the 663SQT-UL.DS fits. It differs in that it also carries an exterior cylinder, so the door can still be keyed from the corridor.
19) Which deadbolt has an adjustable backset if I do not know whether the door is bored 2-3/8 or 2-3/4?
The Kwikset 663SQT-UL.DS ships with a 2-3/8 inch round corner latch, so the bore needs to match that backset. Where the backset is unknown or varies across a building, the Cal-Royal ED500 is a Grade 3 single cylinder deadbolt with adjustable backset for 1-3/8 inch to 1-3/4 inch doors, and the Brinks Raleigh E2401 and Mendocino E2402 both use a 4-way adjustable backset. The Falcon D111 also offers an adjustable backset in a Grade 1 unit. Each of those is cylinder x thumbturn rather than one-sided.
20) Is the Baldwin 8BR0618001 deadbolt spacer a substitute for the Kwikset 663SQT?
No. The Baldwin Reserve 8BR0618001 is a spacer used with a double cylinder deadbolt, and the BEST 8T is a tube component from the T Series tubular deadbolt line. Both are pieces that go into or alongside a lock, not a working deadbolt. The Kwikset 663SQT-UL.DS is a complete one-sided turn deadbolt supplied with a 2-3/8 inch round corner latch, dual RCS strike plates, and a 5303 full lip strike.
21) We want the deadbolt and the entry latch operated together on one lever. Does that exist?
The Kwikset 663SQT-UL.DS is a standalone deadbolt with no latchset function. If the door needs one device combining the two, the Falcon H2101 is a Grade 2 entrance interconnected lock with a single cylinder deadbolt, which retracts the latch and deadbolt in one motion. The Baldwin Estates 8011 is a different arrangement again, a contemporary 1-5/8 inch double cylinder deadbolt in an entrance function. Interconnected units use a different door prep than a separate bored deadbolt.
22) What single cylinder deadbolt has a 1 inch throw for a commercial opening?
The Hager 3215 is a single cylinder deadbolt with a 1 inch throw, a Grade 2 commercial lock carrying a fire rating and fitting 1-3/8 inch to 1-3/4 inch doors, the same thickness range the Kwikset 663SQT-UL.DS is built for. It differs in operation: the Hager unit is cylinder x thumbturn, so it is keyed from outside, while the 663SQT-UL.DS works from the interior turn only.
23) Does the Kwikset 663SQT deadbolt have an antimicrobial coating?
Yes, the 663SQT-UL.DS is a Microban product. That matters most on high-touch openings in healthcare, education, and multi-family common areas, where the thumbturn gets handled constantly. It's a surface treatment on the hardware, not a substitute for a cleaning protocol.
24) Can one person install the Kwikset 663SQT deadbolt on an already-bored door?
On a door already bored for a 2-3/8 inch backset deadbolt, yes: it's a screwdriver-only job, no drilling. Because there is no exterior cylinder, there's no keyway to align, which removes the step that usually gets fumbled. The frame side is where the work is, and you have both RCS strike plates and the 5303 full lip strike included to match the existing jamb cutout.
25) Which matte black or satin nickel deadbolt matches the Kwikset 663SQT if I need a keyed one on the same corridor?
The Kwikset 663SQT-UL.DS comes in Satin Nickel, Bright Chrome, and Matte Black. For a keyed unit in the same square styling, the Bravura 310SC Elite is a Grade 2 contemporary square deadbolt and the Bravura 910005 is a Grade 2 rectangle deadbolt, both cylinder x thumbturn. In a brushed stainless family, the Delaney LU Series 320601 is a Grade 2 double cylinder deadbolt in stainless steel US32D, and the Delaney LM Series 301702 is Grade 1 in dull chrome US26D. Confirm the finish code against what is already hung before mixing lines on one corridor.
26) Is a Detex hinge side deadbolt an alternative for securing an exit door?
It solves a different problem. The Detex DX Series is a hinge side locking deadbolt with multi-point security, throwing bolts on the hinge edge of the door. The Kwikset 663SQT-UL.DS is a single bolt on the lock edge, operated by an interior thumb-turn. The DynaLock 1300 Series is a heavy duty mortise electric deadbolt, released by power rather than by hand. Neither is a drop-in for a bored one-sided turn deadbolt; each needs its own prep and, for the DynaLock, a power supply and release path.
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Does the Kwikset 663SQT-26.UL.DS come with a warranty?
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