Mortice lock /Yale/Poland/Secure%20your%20home/shed/Mortice-lock-524x224.jpg Mortice locks can be operated by a cylinder or by integral levers. The higher the number of levers, the more security the lock provides. Most insurance companies require that external timber doors are secured by a British Standard 5 Lever Mortice Lock. Look for the kitemark when specifying and purchasing products. Internal doors and those on outbuildings can be secured by a 2 or 3 lever lock. A sashlock is operated by handle and key and a deadlock is operated by key only.