Butt Set Recognized as the new industry standard, the MT-8001 butt set provides superior quality at an affordable price. With its high impedance monitor for data safe operation, technicians can clip onto a line in Monitor mode without disrupting existing traffic. Prokit's unsurpassed protection standards and durability assure the butt set will keep working even in the toughest environments. New weatherproofing provides enhanced resistance to severe weather conditions. Built-in amplified speaker provides three audio levels for hands free listening. Functional tone and pulse mode applied to most telephone system. Store up to twelve, 16-digit telephone numbers in speed dial. Pre-dialing and last number redial operation save up to 32-digit telephone number Advanced PBX pause function easily inserted between digits of a stored number High-impedance monitor mode design provides minor noise output while operating. Equipped with the mute switch to turn off the speakerphone microphone for privacy. Continuous polarity LED indications, easy to verify and detect the current connection status. Power saving function automatically shut down after 5 minutes of inactivity, providing longer operating time. Audible electronic ringer in 3 level volume controls. Ergonomic and lightweight design, enjoy unparalleled mobility and reliability. Used as a regular telephone while positioning the “Talk/Monitor” switch in talk mode. Product does not contain batteries. Electrical Loop limit 2 kΩ maximum at 48 VDC(nominal 20 mA minimum loop current) DC resistance Talk mode 300Ω typical Monitor impedance 39kΩ nominal at 1 kHz Rotary dial output Pulsing rate 10pps+0.8pps Percent break 61%±2% Interdigit interval 1000 ms typical Leakage during break >50 kΩ DTMF output Tone frequency error ±1.2% maximum Tone level -8±2dBm combined(typical) High versus low tone difference 4 dB maximum Memory dialing Memory capacity 12 memories plus last number redialing Digit capacity 16 digits per memory PBX pause duration 4 seconds Monitor amplifier power source 9V transistor; provides 25 hours continuous use, typical Speaker levels Low, medium, high Automatic power shut off After 5 min. of no audio signal Speaker phone levels Low, medium high Power source Shared line and 9V(6F22) battery power Physical Length 10-1/4 inches(26.0 cm) Width 2-3/4 inches(7.0 cm) Height 3-1/2 inches(8.9 cm) Weight 560 g typical Environmental Temperature Operating:0 to 50˚CStorage:-40 to 66˚C Altitude relative humidity To 10,000 feet 5 to 95%