Extech 461830 Digital StroboTach Checks and analyzes motion and speed by simply aiming and synchronizing it's flash rate (FPM) with a rotating object Read RPMs on 4 digit LED display Duty cycles from 5 to 30 minutes and 1 second sampling time Ideal for measuring the speed of moving gears, fans, pumps, motors and equipment used in general maintenance and production High accuracy over a wide, dynamic range via exclusive microcomputer LSI circuit and crystal control time-base