The Yale 81 rollerbolt nightlatch front door lock has a rollerbolt for push/pull action making it ideal to prevent accidental lock out. Ideal for communal or flat entrance doors. It is opened by a key from the outside and a turn handle operation from inside. The 81 rollerbolt nightlatch has a 60mm backset, this is the measurement from the edge of the door to the centre of the keyhole. Locks with a 40mm backset are normally used where there is restricted space, such as on a narrow glass panelled door. 10 Year Guarantee. Case Finish Dark Metallic Grey. Cylinder Finish Polished Brass. Backset 60mm Supplied with 2 x keys Security Rating Standard.