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Polished brass mortise lockset with ornamental knobs and double cylinders

Marks USA

Marks USA 21AC/3-W-LHR Polished Brass Left Hand Reverse Double Cylinder Mortise Door Lock

SKU CH-DWJV-3JDCX MPN 21AC/3-W-LHR

Double cylinder mortise lockset with through-bolted solid brass Unilock trim for out-swinging doors

  • Location typeLeft Hand Reverse (For Out-Swinging Door)
  • Backset distance2-1/2 in
  • Lock keyingKeyed Different
  • Main functionDouble Cylinder
  • Surface finishPolished Brass
  • Sold asBox
  • Left-hand-reverse handing suits out-swinging doors
  • Double cylinder operation needs a key on both sides
  • Through-bolted solid brass trim resists forced entry
  • 1-inch deadbolt throw adds strong locking depth
  • Polished brass finish provides lasting corrosion resistance

Polished Brass Mortise Entry Lockset

The Marks USA 21AC/3-W-LHR is a double-cylinder mortise lockset finished in polished brass for residential or light commercial doors. It uses an ornamental Unilock knob and plate assembly that is through-bolted for secure mounting. The lock operates with two solid brass cylinders and includes two keys for exterior and interior operation.

Suits Out-Swinging Doors With 2-1/2" Backset

This unit is handed Left Hand Reverse, meaning it is built for out-swinging doors where the hinges are on the left viewed from outside. Buyers with in-swinging doors or a different backset dimension should look at another model. The lock fits door thicknesses between 1-3/8" and 1-3/4" only.

Double Cylinder Function Requires Key On Both Sides

The defining specification is the double-cylinder mechanism: a key is needed to lock or unlock the 1" deadbolt from either side of the door. This provides added security for doors with adjacent glass but prevents quick exit without a key in an emergency. Check local fire codes before installing.

How it compares

Measured against everything we stock in Door Lock Sets & Deadbolts, at today’s prices. Recalculated every night.

Price $113.99
Pricier than about 69% of the 2,145 comparable items (median $55.99).

Specifications

Product
Brand nameMarks
Product line21AC
Model name21AC/3-W-LHR
Product typeOrnament Unilock Knobe Mortise Lockset
Design styleKnobs
Size & build
Surface finishPolished Brass
Main materialBrass
Backset distance2-1/2 in
More details
Location typeLeft Hand Reverse (For Out-Swinging Door)
Lock keyingKeyed Different
Main functionDouble Cylinder

Questions about this item

Does the 1" deadbolt generate any noise or heat when the lock is operated repeatedly throughout the day?

The mechanical deadbolt operates silently and produces no heat during normal use, as it relies solely on manual key turning without any powered components.

What door thickness and preparation must already exist for this mortise lockset to install correctly?

The lock fits doors 1-3/8" to 1-3/4" thick and requires a standard mortise pocket cut to accept the 1" x 7-1/8" face plate with a 2-1/2" backset.

Will the polished brass finish and Unilock knob trim match the style of older brass hardware already on the property?

The polished brass finish and ornamental Unilock knob/plate design are consistent with traditional brass hardware, allowing visual continuity with existing period fittings.

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