The Master Lock Grade 1 Double Cylinder Deadbolt features a double cylinder deadbolt with interior and exterior keyway. The deadbolt is four way adjustable for 2-3/8 inches or 2-3/4 inches backset, with square or rounded corner strike plates. It offers ANSI Grade 1 performance for exterior locking applications and operates with SC1 cylinder. The 25 Mechanical 5 Finish Warranty provides peace of mind from a brand you can trust.