Nightlatches are a common locking product found mainly on residential front doors. They ordinarily feature a single sprung latch locking point which engages automatically when the door is shut, securing the property.
The Yale PBS1 High Security Nightlatch lock has been approved to BS 3621:2007, BS EN 12209:2003 and BS EN 1303:2005 the highest level of certification currently available making them one of the best available from the original Yale lock inventor.