Category Alarm Systems > #    Mintron™ Lock Chassis: Cold rolled steel with zinc dichromate finish for corrosion resistance. Latch retractor is precision cast steel. Requires standard 2-1/8" (53.97 mm) bore through door. Backset: 2-3/4" (69.85 mm) backset standard, 3-3/4" (95.25 mm) and 5" (127 mm) available.