Automatic Noise Cancelling ANC feature for proper operation in noisy environments- Vandal Resistant Features: 14 gauge louvered 316 stainless steel faceplate with permanent laser etched graphics, speaker/mic screen, heavy duty metal In.CallIn. button and T-10 Torx security mounting screws and drive bit- Weather Resistant Features: Marine grade 316 stainless steel faceplate, screws and push button switch. Switch internally sealed per IP67. Mylar speaker. Self-draining mic mount. Faceplate, mic and speaker gaskets- Telephone line powered- Non-volatile E2 memory no batteries required- Programmable to dial up to 5 numbers on busy / ring no answer- Blue off-hook LED indicator- Volume adjustments for microphone and speaker- Advanced call progress detection: disconnects on busy signal, return to dial tone, CPC, reorder tone, maximum call time out and programmable silence time out- Selectable auto-answer feature for monitoring- Extended temperature range -15 Degrees F to 130 Degrees F- E-32 flush mounts in a standard double gang box not included- Optional PB-1 Panic Button Kit DOD# 233