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Polished brass mortise entry lockset with screw-on knobs and thumb turn

Marks USA

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

SKU CH-YZ6V-HM4QM MPN 91A/3

Right-hand mortise entry lockset with surface-mounted brass plates, screw-on knobs, swivel spindle and solid brass cylinder supplied with two keys

  • Backset distance2-1/2 in
  • Lock keyingKeyed Different
  • Main functionEntrance
  • Surface finishPolished Brass
  • Sold asBox
  • Product typeMortise Entry Surface Mounted Lockset
  • Solid brass construction resists corrosion
  • Surface-mounted plates simplify installation
  • Screw-on knobs with swivel spindle ensure smooth operation
  • Right-hand mortise design fits specific door swings
  • Two keys included for immediate use

Right-hand mortise entry lock

The Marks Metro 91A/3 is a surface-mounted mortise lockset finished in polished brass. It uses screw-on knobs with a swivel spindle and includes a solid brass cylinder supplied with two keys. The lock is designed for right-hand doors and provides an entrance function with a deadbolt. It fits a 2-1/2 inch backset and a front face plate measuring 1-1/16 by 7-5/8 inches.

Installers needing a surface-mount mortise set

This lock suits projects where a mortise mechanism must be mounted on the door surface rather than recessed. It is not for doors prepped for a standard cylindrical latch, nor for left-hand swings where the handing cannot be changed. Buyers who need a different backset or a lever handle instead of knobs should look at other models. The keyed-different cylinder means each lock opens with its own keys.

2-1/2 inch backset

The backset is the single dimension that decides whether this lock fits the existing door preparation. A 2-1/2 inch measurement matches many commercial and heavy-residential doors but will not align with the common 2-3/8 inch residential standard. Verify the door drilling before ordering, as the surface-mounted plates cover the mortise pocket but do not adjust the spindle centre.

How it compares

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

Price $72.99
Pricier than about 57% of the 2,145 comparable items (median $55.99).

Specifications

Product
Brand nameMarks
Product lineMetro
Model name91A/3
Product typeMortise Entry Surface Mounted Lockset
Design styleKnobs
Size & build
Surface finishPolished Brass
Main materialBrass
Backset distance2-1/2 in
More details
Lock keyingKeyed Different
Main functionEntrance

Questions about this item

Will the solid brass cylinder need lubrication or replacement over time?

The solid brass cylinder ships with two keys and is built for commercial-grade cycles; periodic graphite lubrication keeps the action smooth without replacing the cylinder.

What limits continuous operation on a high-traffic entrance?

The 1" deadbolt throw and 2-1/2" backset are designed for heavy use; the first limit is typically latch wear on the strike plate rather than the lock body itself.

Does the brass finish or mechanism generate noticeable heat or noise after all-day use?

Mechanical mortise locks produce no heat and only a quiet click on each operation; the polished brass plates remain at ambient temperature.

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