Finish: Polished Brass FinishForend: BrassBox Strike Assembly: Painted to match forendCase Finish: Silver powder coatCase Size: 80mm x 108mm (3in)BackSet: 53mm This is the measurement from the edge of the door to the centre of the keyhole.Centres: 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.