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Polished brass right-hand mortise door lock with screw-on knobs and face plate

Marks USA

Marks USA 91D/3 Polished Brass Right Hand Mortise Door Lock

SKU CH-X2Z6-Y2BSH MPN 91D/3

Right-hand mortise lockset with classroom function, polished brass finish and 2-1/2" backset

  • Backset distance2-1/2 in
  • Lock keyingKeyed Different
  • Main functionClassroom
  • Surface finishPolished Brass
  • Sold asBox
  • Product typeMortise Surface Mounted Lock Knob, Office Vestibule, Passage
  • Solid brass plates resist daily wear
  • 2-1/2" backset fits standard door prep
  • Classroom function keeps outside locked by key only
  • Right-hand configuration matches door swing direction
  • Surface-mounted screw-on knobs simplify installation

Product Identity

The Marks USA 91D/3 is a right-hand mortise lockset in polished brass, built for commercial office vestibules and classroom doors. It operates as a passage set that stays open or a storeroom set that stays locked, with a latch-and-rocker mechanism and no deadbolt.

Function Upgrade

This lockset replaces cylindrical knob locks that lack a mortise case and vestibule flexibility. The jump is worth it when a project demands a solid-brass mortise body, a 2-1/2" backset, and the ability to switch between always-open and always-locked modes without changing hardware.

Capacity Limits

The solid brass cylinder and two keys handle daily commercial traffic and standard keyed-different access control. It runs out where a deadbolt is required for high-security perimeters, where a left-hand door orientation is needed, or where an interior thumb-turn is specified for egress.

How it compares

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

Price $94.99
Pricier than about 64% of the 2,145 comparable items (median $55.99).

Specifications

Product
Brand nameMarks
Product lineMetro
Model name91D/3
Product typeMortise Surface Mounted Lock Knob, Office Vestibule, Passage Always Open OR Storeroom Always Locked, Classroom, Latch and Rocker (No Bolt) Lockset
Design styleKnobs
Size & build
Surface finishPolished Brass
Main materialBrass
Backset distance2-1/2 in
More details
Lock keyingKeyed Different
Main functionClassroom

Questions about this item

What door thickness and backset does the 91D/3 mortise lock require?

The lock is built for a 2-1/2" backset and a face plate measuring 1-1/16" by 7-5/8", so the door must accommodate those dimensions.

How are the screw-on knobs and swivel spindle fitted during installation?

Mount the surface-mounted plate assemblies on each side of the door, then thread the knobs onto the swivel spindle and secure them with the supplied screws.

When will the solid brass cylinder or latch components need servicing?

The solid brass cylinder and latch are designed for long commercial life; periodic lubrication of the latch bolt and cylinder is the only routine maintenance required.

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