<P> A dead bolt, deadbolt or dead lock is a locking mechanism distinct from a spring bolt lock because a deadbolt cannot be moved to the open position except by rotating the key . The more common spring bolt lock uses a spring to hold the bolt in place, allowing retraction by applying force to the bolt itself . A deadbolt can therefore make a door more resistant to entry without the correct key . </P> <P> A deadbolt is often used to complement a spring - bolt lock on an entry door to a building . </P>

What is a deadlock lock on a door
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