CM-120 Series keypads are North American-built and provide Tri-Brid (TM) stand alone, Wiegand, and optional wireless operation. CM120i offers the best performance and value for indoor applications. CM-120wV2 is a vandal and weather-resistant model with a metal back-lit keypad. CM-120 Series hardwired keypads have added wireless functions by plugging in a CM-TX99 wireless transmitter module. CM-120TX Keypads are fully wireless with battery power. A CM-RX 91/92 Series receiver is required, sold separately. Lithium batteries are recommended for CM-120TX for environments below 0°C (32°F).