Yale BS1 Maximum security nightlatches are British Standard approved to ensure the highest level of security. They are recommended by insurance companies and have achieved kitemark status BS 3621:2007. It has a 60mm backset which is the measurement from the edge of the door to the centre of the keyhole. The internal handle is lockable for increased security. The latch automatically deadlocks on closing the door and the snib function enables the latch to be held back. Its available in chrome, Brass and dark metallic grey finish.