An unlocked door is simply an open invitation to a thief. We recommend this lock because it is very sturdy and difficult to open without a key on either side. When the house is occupied, a key should always be left in the keyhole as a means of fast exit in case of a fire. Always remove the key when leaving home. If a burglar breaks in another way, such as a window, don't provide an easy point of exit through the door.
Deadbolts also come with single-cylinders.
Single cylinder deadbolts are still very good, however in other applications. This method of entry is common in apartment buildings where cheap spring-latch or cylindrical tubular locks are installed. A dead-latch is the most common lock found in apartments and most homes today. This lock is not recommended because it is easily opened and offers very minimal security. It is less expensive than the other types of locks, but equally effective for security if bolted through the door rather that screwed in. 5.