Simplex 5021B - Combination Entry/Key Override (Best compatible  included) Industrial strength 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 5000 Series is an ANSI rated Grade 1 security lock that is highly weather resistant.  Entry is gained via a 1 to 5 digit code that is sequential.  Vandal resistant, the Simplex series of PIN based locks have found widespread acceptance in high-traffic commercial, institutional, and government buildings.