https://www.openlearning.com/u..../pappasepstein-slxqi
L4V Hook Deadlocks L4V hook-deadlocks make a great upgrade for the back and side van doors as well as tailgates or doors to the cab. They operate independently of the locking system and are secured with high-security keys. Specially designed to ward off attacks of 'peel and steal' this product has been tested by an independent lab increasing resistance by up to 300 percent. It is ideal for multi-drop couriers as well as applications where the driver might forget to lock the vehicle door.