A deadbolt lock is “a lock bolt that is moved by turning a knob or key without the action of a spring.” In simple words it is a lock that can be opened only through a key or knob and cannot be easily battered or bored. They tend to resist any forced entry into the house and thus offer a good security to the house. The bolt must extend to one inch in diameter and should be made of hardened steel. The collar of the cylindrical locks must properly tapered and be free spinning so that it is difficult to grip it with a pliers or wrench. The connecting screw must be on the inside and made up of solid steel. No exposed screw heads should be present or seen. The connecting screws must be at least 1/4 inch in diameter and go into solid metal shock, not screw posts.