The Yale PM444 series security door bolts are concealed (mortice fixed) into the door with a bolt which throws into the door frame. Operated by using the key supplied giveing added securiy and extra protection to your home.
The Yale YALPM444KB is 1 x Additional Key Only for PM444 Door Security Bolts. The additional key is ideal to store in a safe place in case of misplacement of the original key.