Costar Brand Model 12-24SIR UL Listed Power Input - Allows for input of 12 or 24Vdc False Alarm Resistant Low Current Draw-Standby 60 microamps, Trouble or Alarm 25 milliamps Continuously self-tests every 10 minutes Supervises sensor and alarm circuit status Non-Latching, Automatic reset with dual relays Storage - Operating: 40 to 100 degrees Fahrenheit Solid state infrared (SIR) sensor with reservoir system 85dB @ 10 feet 12 or 24Vdc Nominal, operating voltage range 10-28V 14-22 AWG wiring Wall or Ceiling mount DIMENSIONS: 5" diameter, 1.75" height Alarm Response Times - CO level 30 parts per million-No response for 30 days CO level 70 parts per million-Response within 60-240 min. CO level 150 parts per million-Response within 10-15 min. CO level 400 parts per million-Response within 4-15 min. Alarm Signals- (Normal)Red LED flashes every 30sec. to indicate alarm is powered. (Alarm)Flashing Red LED and pulsating horn. (Trouble/Service)Red LED flashes twice,horn beeps once every 30 sec. (Test)One chirp, Red LED flashes 4-5 times followed by 2 alarm signals PLEASE NOTE THE SHIPPING AND RETURN POLICIES NEAR THE BOTTOM OF OUR HOME PAGE. THANK YOU.