Rollerbolt operated by lever handle from either side. Deadbolt operated by key from either side using a double cylinder (not supplied) or by key outside and thumb turn inside using a cylinder thumb with turn(not supplied). 76mm and 101mm sizes are pierced to accept 38mm centre horizontally and 38mm centre diagonally opposed bolt through fixing furniture; 63mm size pierced diagonally only. Rollerbolt is brass and reversible; projection is 12mm. Deadbolt is also brass with two hardened steel rollers and the throw is 14mm. The measurements are as follows: 63mm(A) lock come with 45mm(B) backset and 48.5mm(C) centres, 76mm(A) lock comes with 57mm(B) backset and 48.5mm(C) centres, 101mm(A) lock comes with 82mm(B) backset and 48.5mm(C) centres