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 lock cylinder with 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.

These are commonly installed where there is only a key and knob set on the door. 
This lock has to be physically locked with a key when you close the door. 
Once the lock is locked, you will need a key from either the outside or the inside to throw the bolt over to the unlocked position.
This style of lock will be left in the unlocked position when you’re inside the property, 
as you will use the key and knob set as your main locking device.


In the U.S. there are two common backsets for residential locks, 2-3/8" and 2-3/4". 
The backset is the distance from the edge of the door to the center of the spindle/handle. 
We will pack your deadbolt with a 2-3/8" or 2-3/4" backset depending on which backset you specify.