Simplex L1021 - Combination Entry & Prepped for Key Override  (Use your own , or order one from us at checkout) Tough-as-nails combination lock from the leader in top-of-the-line security solutions, dormakaba. dormakaba has been making high-quality security products for over 100 years.  The Simplex L1000 Series is a 3-hour UL/ULC fire-rated stand-alone security lock that is highly weather resistant and certified for durability, as it complies with D.O.D (Dept. of Defense) 5220.22M.  Entry is gained via a 1 to 5 digit code that is sequential.  Vandal-resistant, the Simplex locks have found widespread acceptance in high-traffic commercial, institutional, and government buildings.