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 “Call” 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 F to 130 F E 32 flush mounts in a standard double gang box not included Optional PB 1 Panic Button Kit DOD# 233