Features and Specifications Access Master 2 channel/button transmitter, compatible with models manufactured from 1997-present 390 MHZ Frequency, over 100 billion codes with code rotating technology Visor clip and Lithium battery (5 years life w/normal use) included Compatible with ALL Security+ systems, including Chamberlain, Sears, Craftsman and Raynor code rolling residential openers (Safety Signal) Chamberlain 950CB, 953CB, 956CB ^ Sears Craftsman Compatible Model #'s 139.53661 139.53677SRT 139.53661SRT 139.53677SRT3 139.53661SRT3 139.53680 139.53662 139.53681 139.53662SRT2 139.53684 139.53663 139.53961 139.53663SRT 139.53961SRT 139.53664 139.53962 139.53664SRT 139.53962SRT 139.53664SRT2 139.53962SRT1 139.53670 139.53963 139.53670SRT1 139.53963SRT 139.53671 139.53964 139.53671SRT 139.53964SRT 139.53671SRT3 139.53966 139.53672 139.53966SRT 139.53672SRT 139.53966SRT1 139.53672SRT2 139.53974 139.53672SRT3 139.53974SRT 139.53673 139.53975 139.53673SRT 139.53975SRT 139.53673SRT3 139.53975SRT1 139.53674 139.53976 139.53674SRT1 139.53976SRT 139.53674SRT2 139.53978 139.53675 139.53978SRT 139.53675SRT2 139.53978SRT1 139.53677 ^