Simplex 1021C-3 Brass US3 Mechanical Knob Pushbutton Combination Door Lock

Mechanical knob combination lock

The Simplex 1021C-3 is a heavy-duty cylindrical lock with a pushbutton keypad that grants exterior access by code while allowing free egress. It is built for doors 35 to 57 mm thick and accepts LFIC Corbin Russwin 6-pin length cores, which are sold separately. The brass US3 finish suits commercial and institutional settings that prefer a mechanical solution over electronic alternatives.

Adjustable backset and fire-rated latch

The lock ships with an adjustable backset covering 60 mm and 70 mm positions and a 13 mm latch throw, so one unit fits both common door preparations without extra parts. A unified trim plate and cast front housing add rigidity, and the assembly carries a three-hour UL/ULC fire rating on "A" label doors, removing the need for separate fire-rated hardware in many installations.

Surface mounting with template alignment

Installation follows a standard cylindrical prep: drill the face bore and edge bore, mount the latch, then secure the through-bolts and unified trim. The single access code is programmed at the keypad without removing the lock from the door. The most common issue is misaligned latch engagement caused by an incorrect backset selection or an off-centre face bore; verifying the 60 mm or 70 mm setting against the door prep before tightening prevents callbacks.