Arrow MK18 Communicating Classroom Knob Lock

Arrow MK18 Dead locking latch bolt operated by knob one side onlyexcept when knob is locked by key. Non removableblank trim outside. Arrow's MK Series offers security professionals simple solutions to accessibility requirements. The MK Series designs, architectural finish, and available function options make it ideal for commercial applications where heavy-duty Grade 1 hardware may not be necessary. Features Lock Chassis: Cold rolled steel with zinc dichromate finish for corrosion resistance. Requires standard 2-1/8" (53.97 mm) bore through door.Backset: 2-3/8" (60.32 mm) standard. 2-3/4" (69.85 mm), 3-3/4" (95.25 mm) available.Door Thickness: 1-3/8" (34.92 mm) to 1-3/4" (44.45 mm)Latch: Brass with 1/2" (12.7 mm) throw. Latch housing is steel, with zinc dichromate finish for corrosion resistance. 7/8" (22.225 mm) bore in edge of door is required.Latch Front: Brass or bronze. Standard faceplate for 2-3/8" (60.32 mm) backset measures 2-1/4"