In-Duct Diagnostic Psychrometer With Telescopic Probe.Specifications:Battery 9V,Battery Life 150Hrs Typical Alkaline,Sensor Type Thermistor And Capacitive Polymer Film,Measurement Range Relative Humidity:0 To 100,Temperature:-4 To 104Degf(-20 To 60Degc.)38" Telescopic Probe Laser Etched To Measure Location Of Teat Point In Duct.Bright Blue Backligth Easily Read The Lcd In The Dark.Rubber Clips Attach The Probe To The Side Of The Meter For One-Handed Testing,Magnetic Hanger Free Up A Hand.Weight:2.85 Pounds, Mfg/Box.