MASTER KEY FOR MASTER LOCK MODEL SERIES 1 2 3 4 5 6 11 34 35 36 37 39 40 187 190 311 312 315 317 430 443 475 AND 631. THE MASTER KEY ALLOWS THE FACILITY ADMINISTRATOR TO OPEN THE PADLOCK WITHOUT USING THE INDIVIDUAL KEY OR COMBINATION. MASTER LOCK CONTROL KEYS CAN ONLY BE PURCHASED THROUGH AN OFFICIAL BUSINESS OR ORGANIZATION ACCOUNT. A KEY CODE IS REQUIRED FOR AN EXISTING INSTALLATION. THE LOCK IS NON-CANCELLABLE AND NON-RETURNABLE.