Suitable for Subzero Environments. 40™C (-40™F) to +60™C (+140™F). North American Listed for All Hazardous Groups. cUL / UL Listed. Replaces Explosionproof Telephones w/o Replacing System Cable in Most Applications. Braille Metallic Keypad. ™Shrill™-Type Penetrating Ringer. Noise-Cancelling Microphone. Volume control handset. Low Sidetone for Noisy Environments. Switchable Power Supply - 110VAC/220VAC. Hytrel™ Coil Cord for Maximum Durability. Hearing Aid Compatible (HAC).