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Polished brass door knob and plate set, thru-bolted, pair

Marks USA

Marks USA K21AC/3 Polished Brass Unilock Knob Plate Assembly Kit Thru Bolted door lock

SKU CH-GAK1-PA74J

A polished brass knob and plate assembly kit, thru-bolted for secure fitting on mortise locks, supplied as a pre-assembled pair with screws for two door thicknesses

  • FinishPolished Brass
  • TypeUnilock Knob / Plate Assembly Kit Thru Bolted
  • Pre-assembled knob and plate speeds installation
  • Thru-bolted design adds strength to the assembly
  • Fits both 1-3/8" and 1-3/4" door thicknesses
  • Spring-loaded 9/32" square spindle ensures smooth operation
  • Polished brass US3 finish resists corrosion and wear

Marks USA Unilock Knob Plate Kit

This Marks USA K21AC/3 kit supplies a polished brass Unilock knob and plate assembly for mortise locks on ornamental iron gate doors. The spring-loaded spindle measures 9/32 inch square and the set is thru-bolted for secure mounting. It replaces Marks USA #21AC mortise lock knobs and arrives with the knob and plate already pre-assembled. Each package contains one pair.

Installation ease and common issues

The pre-assembled knob and plate reduce fitting time because no separate alignment of those parts is required. Thru-bolted mounting uses the supplied screws for either 1-3/8 inch or 1-3/4 inch door thicknesses. The only frequent issue is selecting the wrong screw set for the actual door thickness, which can leave the hardware loose.

Compatibility checks before ordering

Verify that the existing mortise lock is a Marks USA 21AC model so the 9/32 inch square spindle engages correctly. Confirm the door thickness matches one of the two supplied screw lengths to avoid a poor fit. Ensure the ornamental iron gate door uses a Unilock style knob rather than a different knob design.

Highlights

  • Pre-assembled knob and plate speeds installation
  • Thru-bolted design adds strength to the assembly
  • Fits both 1-3/8" and 1-3/4" door thicknesses
  • Spring-loaded 9/32" square spindle ensures smooth operation
  • Polished brass US3 finish resists corrosion and wear

Specifications

FinishPolished Brass
TypeUnilock Knob / Plate Assembly Kit Thru Bolted

Questions about this item

How do I confirm the 9/32" spring-loaded spindle operates correctly after installation?

Turn each knob; the latch should retract smoothly and snap back when released, confirming the spindle engages the mortise lock as intended.

What hardware is included for 1-3/8" and 1-3/4" doors?

The kit supplies thru-bolts and screws sized for both door thicknesses, plus the pre-assembled knob-and-plate pair; no extra fasteners are required.

Which finish matches existing Marks USA #21AC mortise lock trim?

The Polished Brass US3 finish is the direct replacement for the original #21AC ornamental iron gate hardware.

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