2277 3 Lever Mortice Sashlock Satin Chrome 77.5mm 3in Visi

Case Size 77.5mm
Backset: 57mm This is the measurement from the edge of the door to the centre of the keyhole.
Centre: 57mm This is the measurement from the centre of the follower, which operates the handles, to the centre of the keyhole. In the UK this is commonly 57mm.
Forend Satin Chrome