Cast aluminum enclosure. Metallic Hookswitch. 15" Lanyard embedded armored handset cord: Resists up to 500 pounds of pull strength. Sealed Metallic Braille Keypad (226-001, 226-001VC). Extremely Vandal Resistant Tamper-resistant Hardware. Extreme Operating Temperature Range -40°C (-40°F) to +60°C(+140°F). Hearing-Aid Compatible (HAC). Volume Control and Noise Canceling Handset. FCC & IC Certified, UL60950 Listed.