KDT2967 Features: -Range: 100 to 4000 RPM (clockwise or counter-clock wise).-Diameter: 2-3/4".-Hand Held Tachometer 100 to 4000 RPM. Construction: -Tachometer checks diesels, pumps, compressors, power take-offs and farm and construction equipment revolution speed. Dimensions: -Length: 4-1/4"This tool is ideal where electric tachometer can not be used. It"s simple to operate, hold the rubber tip against end of rotating shaft and read the revolution per minute directly from the dial.. Warranty: -Lifetime warranty does not cover abuse.