Backset 60mm Case Finish Brasslux Cylinder Finish Brass BS3621 approved 10 disc AVA cylinder lock. Hardened steel plates & pins, anti drill for additional security. 50,000 differs. The deadbolt is automatically thrown when door closes and withdrawn from knob inside and key outside. Internal knob can be locked by key only. Bolt can be held back by depressing snib on top if the case. This lock is particularly suitable for glass panelled doors. Disc mechanism provides protection against the lock being bumped open. NOTE: NOT RECOMMENDED FOR DIY INSTALLATION. This item previously branded Chubb Locks