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). Deadbolt is brass with two hardened steel rollers and the throw is 14mm. The measurements are as follows: 63mm(A) lock come with 45mm(B) backset, 76mm(A) lock comes with 57mm(B) backset, 101mm(A) lock comes with 82mm(B) backset