Guardian Telecom Weather / Dust Proof Metal Keypad and Armored Cord Features: Exemplified routine boards resistant to water moisture build-up or moisture and dust 16 evaluate deterioration protected precious metal box with dust coat finish Robust professional amount management mobile phone on models 10/30/40 SCT-40 model telephone includes amount management control buttons on handset Corrosion and deterioration resistant metal hardware Electret disturbance reducing microphone Attractive reed hook-switch lowers moving parts subject to wear Service temperature range from -40 C to +60 C (-40 F to +140 F)