Arrow 121 5A Deadlatch Replace...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$51.66
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Arrow 121 5A Deadlatch Replacement Part, MK Series, 2-3/8" Backset, 2-1/4" x 1" Square Corner Face, UL Listed

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Model: 121 5A

In Stock (leaves warehouse same day if ordered before 3pm ET)

$51.66
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Arrow 121 5A Deadlatch Replacement Part, MK Series, UL Listed, Antique Brass

The Arrow 121 5A is a commercial-grade deadlatch replacement part designed for the Arrow MK Series lockset family. Featuring a 2-3/8" backset and a 2-1/4" x 1" square corner face plate in an Antique Brass finish, this deadlatch is precision-engineered to restore reliable latching performance to compatible MK Series installations. UL Listed for verified safety and code compliance, this component is an ideal drop-in replacement for commercial door hardware requiring exact Arrow specifications.

Key Features

  • Precise Backset Dimension: 2-3/8" backset ensures accurate alignment and fitment for standard MK Series door preparations.
  • Exact Face Plate Sizing: 2-1/4" x 1" face plate with square corner profile for a clean, flush installation on commercial-grade doors.
  • MK Series Compatibility: Engineered specifically for Arrow MK Series locksets, providing a reliable factory-spec replacement solution.
  • UL Listed: Meets UL safety and performance standards, supporting code-compliant commercial door hardware installations.
  • Antique Brass Finish: Antique Brass finish matches existing MK Series hardware for a consistent, professional appearance.
  • Commercial-Grade Construction: Designed and rated for commercial applications where dependable latching performance is essential.
  • Arrow Parts Genuine Component: Authentic Arrow replacement part ensuring compatibility and performance consistent with original equipment specifications.

Certifications & Compliance

  • UL Listed
  • Commercial-Grade Rated

Technical Specifications

  • Department: Door Hardware
  • Product Category: Mechanical Locks
  • Product Group: Parts and Accessories
  • Subcategory: Parts and Accessories
  • Product Subgroup: Parts and Accessories
  • Product Type: Latches
  • Parts and Accessories Type: Replacement Parts
  • Commercial/Residential: Commercial
  • Product Model: 121 5A
  • Features: Arrow Parts

Typical Applications

  • Commercial Office Buildings
  • Educational Facilities
  • Healthcare Institutions
  • Retail Establishments
  • Industrial and Warehouse Facilities
  • Multi-Tenant Residential Properties
  • Government and Municipal Buildings

Why Arrow MK Series?

Arrow deadlatch components are built to commercial-grade standards, delivering dependable latching performance in demanding, high-traffic environments. The 121 5A replacement part maintains the precision fit and finish of original Arrow MK Series equipment, ensuring restored functionality without compromise. For facilities requiring UL Listed hardware and verified compatibility, Arrow Parts provide the professional-grade reliability installers and building managers depend on.

Manufacturer Resources

Product Specs

Department:
Door Hardware
Product Category:
Mechanical Locks
Product Group:
Parts and Accessories
Subcategory:
Parts and Accessories
Product Subgroup:
Parts and Accessories
Product Type:
Latches
Parts and Accessories Type:
Replacement Parts
Commercial/Residential:
Commercial
Product Model:
121 5A
Features:
Arrow Parts

Arrow 121 5A – Frequently Asked Questions

1) Will the Arrow 121 5A deadlatch fit a door bored for a 2-3/4 inch backset?
No. The Arrow 121 5A is built to a 2-3/8 inch backset only, so it suits doors prepped with the cross bore 2-3/8 inches from the edge. If your MK Series opening was prepped at 2-3/4 inches, this latch will not line the spindle up with the lock chassis. An adjustable-backset drive-in latch like the Deltana DLP23875, which covers both 2-3/8 and 2-3/4 inches, is the route when you are not sure which prep you have.
2) What size faceplate does the Arrow 121 5A latch use, and will it drop into an existing mortise in the door edge?
The face plate measures 2-1/4 x 1 inch with square corners, which is the standard commercial latch face size. If the existing Arrow MK Series latch mortise in the door edge is a square-corner pocket of that size, the 121 5A drops straight in with no rework. If your door edge is routed with radius (round) corners, the square face will not seat flush without chiselling the corners square.
3) Which Arrow locksets does the 121 5A deadlatch replace?
It is the factory replacement deadlatch for the Arrow MK Series lockset family, model designation 121 5A. It is sold as an Arrow genuine replacement part, not a universal latch, so it is matched to MK Series door prep and chassis dimensions rather than being cross-brand.
4) Is this Arrow latch UL Listed for use in a fire-rated opening?
The 121 5A is UL Listed. That matters on a labeled door, where every component in the lock prep has to carry a listing for the assembly to stay code compliant. Note that the listing statement here is UL Listed without a stated hourly rating; if your specification calls out a specific duration, a latch that states it, such as the Kwikset 83521 RCAL plain latch listed as UL 3 hour, is the safer specification match.
5) Is a deadlatch the same thing as a plain latch, and does it matter which one I order?
It matters. A deadlatch carries an auxiliary deadlocking plunger alongside the main latchbolt: when the door closes and the plunger hits the strike, it blocks the latchbolt from being pushed back, which defeats carding or shimming the latch. A plain latch, such as the Kwikset 84290 square corner plainlatch, has no such plunger and is used on interior passage or privacy openings where that resistance is not needed. For an exterior or tenant entry on the Arrow MK Series, the deadlatching 121 5A is the correct part.
6) What is the closest alternative to the Arrow 121 5A deadlatch if I need a square corner latch with a 2-3/8 inch backset?
The Kwikset 84290 is a square corner plainlatch with a 2-3/8 inch backset and UL designation, the same corner profile and backset as the Arrow 121 5A. The difference is the Arrow 121 5A is a deadlatch built to Arrow MK Series lockset dimensions, so on an MK Series lock it keeps the factory fit and finish; the Kwikset part is built for Kwikset cylindrical locks.
7) I do not know whether the door is prepped for a 2-3/8 or 2-3/4 inch backset. Is there a latch that covers both?
The Arrow 121 5A is a fixed 2-3/8 inch backset part, so the prep has to be confirmed before ordering it. If you need one part that works either way, the Deltana DLP23875 is a drive-in latch with an adjustable backset of 2-3/8 inch or 2-3/4 inch in a passage/privacy function. Note it is a drive-in latch rather than a face-plated deadlatch, and it is not an Arrow MK Series component.
8) Which latch should I use if I need a UL 3 hour fire rating on the opening?
The Arrow 121 5A is a UL Listed commercial deadlatch for Arrow MK Series locksets. If the specification calls out a UL 3 hour latch specifically, the Kwikset 83521 is a plain latch rated UL 3 hour for Kwikset BBL, KNL, CNL and PLL locks, and the Kwikset 83518 is an adjustable square drive UL 3 hour latch. Those two are Kwikset components, so match the latch to the lock family already in the door.
9) What finish does the Arrow 121 5A come in, and will it match my existing door hardware?
One finish only: 609 Antique Brass. On a cylindrical lockset the latch face is the visible strip on the door edge, so if the rest of the MK Series trim on that opening is Antique Brass it will read consistently. Against a satin chrome or oil-rubbed bronze lockset it will not match, and on that opening you want the 121 latch in the matching Arrow finish instead.
10) Is the Arrow 121 5A suitable for a high traffic commercial door, or is it a residential part?
It is a commercial part. Arrow rates the 121 5A for commercial applications and the description points it at offices, schools, healthcare, retail, warehouses, multi-tenant residential, and government buildings. Property managers standardizing on the MK Series across a building can keep this on the shelf as the one latch that services those openings.
11) My existing latch is failing but the lockset is fine. Can I just replace the latch on an Arrow MK Series lock?
Yes, that is exactly what the 121 5A is for. Cylindrical locksets separate the latch unit from the chassis, so a worn or binding latch can be pulled and swapped without touching the knob or lever trim, the cylinder, or the keying. Confirm your prep is 2-3/8 inch backset with a square corner face pocket and the swap is a screwdriver job.
12) Is a drive-in latch like the Deltana DLE23875 a substitute for the Arrow 121 5A?
They are not interchangeable. The Deltana DLE23875 is a drive-in adjustable latch in an entry function, sized for doors 1-3/8 inch to 2 inch thick, and it seats without a screwed face plate. The Arrow 121 5A is a deadlatch with a 2-1/4 inch by 1 inch square corner face plate engineered to Arrow MK Series lockset preparations. If the door already carries an MK Series lock, the Arrow part is the one that matches the existing prep and hardware.
13) I only need the face plate, not the whole latch. Should I order the Arrow 121 5A?
No. The Arrow 121 5A is a complete deadlatch assembly with its face plate attached. For a face plate only, the Emtek 83228 is a faceplate and screws kit with square corners for a tubular pocket door privacy latch. Confirm the lock family first, since the Emtek kit is for Emtek privacy/bed/bath pocket door latches rather than Arrow MK Series hardware.
14) Does this Arrow latch need a separate strike plate, or is one included?
The 121 5A is supplied as the deadlatch unit itself, the latch case and its 2-1/4 x 1 inch square corner face. Strike plates are ordered separately. If you are also replacing the frame strike, Kwikset offers a deadbolt strike plate under 83518, an adjustable square drive UL 3 hour part, though a strike matching the Arrow MK Series prep and your Antique Brass trim is the cleaner match.
15) What is a good alternative if I need a latch for a thicker than standard door?
The Arrow 121 5A is specified by backset and face size rather than by a door thickness range, so for openings outside standard 1-3/4 inch commercial thickness look at a drive-in latch that states its range: the Deltana DLE23875 entry latch covers 1-3/8 to 2 inch doors, and the Deltana DLP23875 covers the same range in passage and privacy. Those are drive-in style, so they suit a door edge with no face-plate mortise.
16) Can I use the Emtek LC9-DBLTCH in place of the Arrow 121 5A?
No. The Emtek LC9-DBLTCH is a motorized deadbolt latch in the EMPowered series, an electrified deadbolt component. The Arrow 121 5A is a mechanical deadlatch for Arrow MK Series locksets and carries no electrified function, so the two serve different openings entirely.
How fast can I get the Arrow 121 5A delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Arrow 121 5A come with a warranty?
Absolutely. The Arrow 121 5A is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Arrow 121 5A?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the Arrow 121 5A from ZenSupply?
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