Bolt 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). Pierced to accept 20mm and 38mm centre bolt through fixing escutcheons. Deadbolt is brass, expanded claw and the throw is 14mm. The measurements are as follows: 76mm(A) lock comes with 57mm(B) backset, 101mm(A) lock comes with 82mm(B) backset