The security Door Security Bolt Locks sometimes called a Rack Bolt is morticed inside the door edge. The bolt can be integrated with Access control units, Magnetic and Electric Door lock systems. They can also be locked or unlocked via a separate splined key or with a fixed splined turn. The bolt has an internal sawtooth rack mechanism into which the splined key ordered separately is inserted. The spline engages with the rack teeth and forms a gearing action that smoothly operates the bolt.