Arrow 121 Deadlatch MK Series ...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$51.66
Image coming soon

Arrow 121 Deadlatch MK Series Replacement Part, 2-3/8" Backset, 2-1/4" x 1" Face, Square Corner, Bright Brass

(No reviews yet) Write a Review

Model: 121 26D

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

$51.66
Adding to cart… The item has been added
Free Shipping on orders over $199
We price match and offer bulk discounts! Click Add to Quote. It's quick and easy.
✨
Earn points with this purchase! You can redeem points for giftcards, iPads, XBox's and more. View Rewards
Free Keying on all locks
You may also like

Arrow 121 Deadlatch MK Series Replacement Part, 2-3/8" Backset, 2-1/4" x 1" Face, Square Corner, Bright Brass

The Arrow 121 Deadlatch is a UL Listed commercial-grade replacement latch 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 a Bright Brass finish, this deadlatch delivers precise fit and reliable operation for commercial door hardware applications. Engineered as a genuine Arrow replacement part, it ensures proper compatibility and performance with existing MK Series installations.

Key Features

  • Backset Dimension: 2-3/8" backset for proper door alignment and smooth latch retraction in standard commercial door preparations.
  • Face Plate Size: 2-1/4" x 1" face plate provides a precise fit within standard mortise pockets for a clean, professional installation.
  • Square Corner Design: Square corner face plate meets standard commercial door prep requirements for seamless replacement.
  • Finish: Bright Brass finish coordinates with matching Arrow MK Series hardware for a cohesive, polished appearance.
  • MK Series Compatibility: Designed specifically for use with Arrow MK Series locksets, ensuring correct fitment and reliable latch function.
  • UL Listed: UL Listed rating confirms the latch meets rigorous safety and performance standards for commercial applications.
  • Genuine Arrow Replacement Part: Sourced directly as an Arrow-branded component, maintaining the integrity and performance of the original hardware assembly.

Certifications & Compliance

  • UL Listed
  • Commercial Grade

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
  • 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 121?

Arrow 121 MK Series deadlatch components are manufactured to strict commercial standards, carrying UL Listed certification to ensure dependable performance in demanding door hardware installations. With precise dimensional specifications including a 2-3/8" backset and 2-1/4" x 1" square corner face, this genuine Arrow replacement part restores lockset function quickly and correctly, minimizing downtime in commercial facilities.

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
Features:
Arrow Parts

Arrow 121 26D – Frequently Asked Questions

1) Will the Arrow 121 deadlatch fit my Arrow MK Series lockset?
Yes. The Arrow 121 is the replacement deadlatch made for the Arrow MK Series lockset family, so it drops into an existing MK Series installation without modifying the door. It carries a 2-3/8 inch backset and a 2-1/4 x 1 inch square corner face. If your door is bored at the 2-3/4 inch backset instead, this latch will not line up with the cross bore.
2) How do I know if I need a square corner or radius corner latch face?
Measure the existing latch faceplate in the edge of the door. The Arrow 121 has a square corner face measuring 2-1/4 x 1 inch, which matches a square, chiseled mortise pocket. If your door edge prep has rounded corners from a router, a square corner plate will leave gaps at the corners and you want a radius (drive-in or round corner) latch instead.
3) Can I use a Kwikset or Deltana latch instead of the Arrow 121 on my MK Series lock?
Not as a like-for-like swap. The Arrow 121 is built to the MK Series lockset's latch tailpiece and hub geometry. The Kwikset 84290 square corner plainlatch is also 2-3/8 inch backset, and the Deltana DLE23875 drive-in entry latch handles 1-3/8 to 2 inch doors, but those are residential-pattern latches for their own locksets. For an MK Series repair, order the Arrow part.
4) Is the Kwikset 84290 plainlatch a substitute for an Arrow 121 deadlatch?
They are not interchangeable in function. The Arrow 121 is a deadlatch built for the Arrow MK Series lockset family, with a 2-3/8 inch backset and a 2-1/4 inch by 1 inch square corner face, and it is a UL Listed commercial replacement part. The Kwikset 84290 is a square corner plainlatch with a 2-3/8 inch backset, also UL. A plainlatch has no deadlocking plunger, so it will not restore the deadlatching action of an MK Series lock, and it is not an Arrow-series component. If the existing Arrow lock chassis stays in the door, stay with the Arrow 121.
5) What should I use instead of an Arrow 121 on a residential door prepped for a drive-in latch?
The Arrow 121 is a commercial replacement latch with a 2-1/4 inch by 1 inch square corner face plate that mortises into the door edge. A door bored for a drive-in latch with no face mortise takes a drive-in style latch instead, such as the Deltana DLE23875 drive-in entry latch or the Deltana DLP23875 drive-in latch with an adjustable 2-3/8 inch or 2-3/4 inch backset for passage/privacy function; both Deltana latches cover doors 1-3/8 inch to 2 inch thick. Match the latch to the lock function you already have on the door.
6) My Arrow MK Series lock needs a new latch and I only have a spare Kwikset RCAL latch - will it work?
No. The Kwikset 83521 RCAL plain latch is built for Kwikset BBL, KNL, CNL and PLL locksets, and the Arrow 121 deadlatch is engineered specifically for the Arrow MK Series so the tailpiece drive and face plate match the original assembly. Keeping the Arrow 121 in the MK Series lock preserves the deadlatch function and the UL Listed rating of the commercial installation.
7) Is the Arrow 121 latch approved for use on a commercial door?
It's a commercial-grade part, and UL Listed, which is why it's used in offices, schools, healthcare, retail, warehouse, multi-tenant residential and municipal buildings. Note it is the latch only, not a fire door assembly rating on its own.
8) What is the difference between a deadlatch and a plain latch, and which do I need?
A deadlatch like the Arrow 121 has an auxiliary deadlocking plunger alongside the latchbolt. When the door closes, the plunger hits the strike and blocks the latchbolt from being shimmed or credit-carded back. A plain latch has no plunger and gives no anti-shim protection, which is fine on an interior passage door but not on an entry. If you're replacing a latch on an MK Series keyed lockset, stay with the deadlatch.
9) My tenant door latch is sticking but the lever still works. Do I have to replace the whole lockset?
Usually not. On an Arrow MK Series lock the deadlatch is a separate serviceable component, so a worn or binding latch can be swapped out on its own with the 121 and the lever, cylinder and keying left alone. That keeps the door on its existing key system and gets the opening back in service quickly.
10) Is the Arrow 121 deadlatch handed?
No handing to specify. The 121 is ordered by backset, face size and finish only, so one part covers left and right hand doors. What you do need to confirm is that the door is prepped for a 2-3/8 inch backset with a square corner 2-1/4 x 1 inch faceplate.
11) I need one latch that works at both 2-3/8 inch and 2-3/4 inch backsets - does the Arrow 121 do that?
The Arrow 121 is a fixed 2-3/8 inch backset deadlatch for the Arrow MK Series, so it suits only 2-3/8 inch prep. If you are stocking a single latch across doors with both backsets, the Deltana DLP23875 is a drive-in latch with an adjustable backset of 2-3/8 inch or 2-3/4 inch in passage/privacy function, and the Kwikset 83518 RCAL is an adjustable square drive latch with a UL 3 hour rating. Neither is an MK Series component, so they are for openings where the lock is being changed rather than for repairing an existing Arrow lockset.
12) Can an Arrow 121 be used on a pocket door privacy latch?
No. The Arrow 121 is a swinging-door deadlatch for Arrow MK Series locksets with a 2-3/8 inch backset. Pocket doors use a tubular pocket door privacy latch, and a square corner part such as the Emtek 83228 faceplate and screws set is the replacement face for that style. The square corner shape is common to both, which is why they are sometimes confused, but the latch bodies are entirely different.
13) For a fire-rated opening, which latch should I specify - the Arrow 121 or a Kwikset RCAL?
The Arrow 121 deadlatch is UL Listed and built as a commercial-grade genuine Arrow replacement for MK Series locksets, so on a fire door already fitted with an MK Series lock it is the part that keeps the assembly as originally listed. The Kwikset 83518 adjustable square drive latch and the 83521 RCAL plain latch both carry a UL 3 hour rating, but they belong to Kwikset lock families. Specify the latch that matches the lock body in the door and confirm the full assembly against the door label.
14) What finishes does the Arrow 121 deadlatch come in?
Six finishes are offered so the latch face matches the trim on the door: 605 Bright Brass, 606 Satin Brass, 612 Satin Bronze, 613 Satin Bronze Oil-Rubbed, 625 Bright Chrome, and 626 Satin Chrome. For a building already standardized on satin chrome MK Series levers, 626 keeps the door edge consistent.
15) Is there a motorized or electrified alternative to the Arrow 121 deadlatch?
The Arrow 121 is a purely mechanical replacement deadlatch for Arrow MK Series locksets. For an electrified opening, the Emtek LC9-DBLTCH is an EMPowered motorized deadbolt latch. That is a deadbolt latch driven by a motor rather than a key-and-lever deadlatch, so it goes with an EMPowered lock assembly, not into an existing MK Series chassis.
16) I need the latch finish to match the rest of the hardware on the door - do the alternatives offer that?
The Arrow 121 deadlatch is offered in 605 Bright Brass, 606 Satin Brass, 612 Satin Bronze, 613 Satin Bronze Oil-Rubbed, 625 Bright Chrome and 626 Satin Chrome, so the exposed face plate can be coordinated with matching Arrow MK Series trim across a building. The Deltana and Kwikset drive-in and plain latches in the same class are catalogued by function and backset rather than by a comparable finish range, so if a visible finish match matters on the door edge, the Arrow 121 finish options are the route.
How fast can I get the Arrow 121 26D 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 26D come with a warranty?
Absolutely. The Arrow 121 26D 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 26D?
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 26D from ZenSupply?
ZenSupply makes it easy to get the commercial door hardware you need—fast shipping, expert support, and rewards on every order. Our team is always ready to help you choose the right product for your project.
!