Duct Detector, 2 Wire, Surface Mounting, Alarm Current 100mA, Standby Current (uA) 70, Depth (In.) 1-7/8, Height (In.) 5.45, Length (In.) 7-3/4, Ambient Temp. Limits (F) -4 to 158, Air Velocity (FPM) 100 to 4000, Alarm Aux. Contact @ 30VDC 2A, Humidity Range ( Percent RH) 93, Voltage 24VDC, Standards UL, ULC, CSFM