Guardian Telecom ACR-11 / ACR-41 - Phone Features: Toss Metal Enclosure Weather, dust & deterioration tolerant for any professional application Spring packed door for automatic closure Attractive reed connect switch to reduce components subject to wear Exemplified build immune to water and harsh agents Joint turns on plastic bushings to avoid performing a result of sodium or corrosion Rise arrestor to prevent current increase damage Robust familiar G type professional handset Volume control to ensure interaction in deafening environments Electret disturbance reducing mic for clear communication Temperature range -40 to +60 C (-40 to +140 F) Waterproof relationships & metal accessories for longer life Clam shell components for easy service Hearing aid compatible Electronic ring for reliability Easily connected to any phone network for popularity on any single range analogue CO or PABX phone line