Operated by thumbturn inside, key outside. Security deadbolts feature full 1" solid core throwbolt, all metal mechanisms, anti-pry shield. DOOR PREP: 2-1/8" Crossbore; 1" Edge Bore; 1" x 2-1/4" Latch Face. BACKSET: adjustable 2-3/8" to 2-3/4". DOOR THICKNESS: Fits 1-3/8" to 1-3/4" doors. CYLINDER: 5-pin. FACEPLATES: 1" x 2-1/4" round corner. STRIKES: 1" x 2-1/4" round corner. BOLT: 1" throw. HANDING: Reversible for right or left handed doors. ANSI/BHMA: Grade 3. "SmartKey" (denoted SMT) feature allows, in 3 steps, locks to be re-keyed to a spare set of keys. When the spare keys are done beingused, the lock can be re-keyed back to the original set of keys; can continually be re-keyed.