The GDI Motortach performs Tacter, Hour meter, and Flash Alert functions on ANY rotating shaft, rotating gear, or pulley. The MotorTACH does NOT require any external power and can be used on Diesel engines, Compressors, Heating motors, Process equipment, Power equipment, Generators, or a host of other equipment. While the equipment is running, the RPM will be displayed on the LCD. When the equipment shuts off, accumulated hours will be displayed. The provided pickup sensor only needs to be within ¼" to pickup a signal! Easy installation. No wire stripping or soldering required. All you need is a 1/8" drill bit and a phillips screw driver. Designed to be functional and user friendly. Specifications Operating temperature: -40F to 160F (-40C to 71C) Shock: SAE J1378 55g Vibration: SAE J1378 20g Humidity: SAE J1378 95% RH 100% Epoxy encapsulated Weight 1 oz Waterproof to 70' below surface UL & CUL recognized, CE approved