Deadbolt operates with a key on the exterior and a key on the interior; for use on exterior doors that need additional security * Unique Snap "n" Stay design holds the deadbolt in place for easy installation * Maximum security deadbolt is ANSI/BHMA Grade 1 and offers superior protection against attacks by crowbar, hammer, wrench, saw, lock pick, and kick-in * Designed for standard door prep (fits existing pre-drilled holes) * Universal latch adjusts to fit 2-3/8? or 2-3/4"