Voltcraft dt 30lk 2 to 200000rpm tachometer voltcraft dt 30lk p the voltcraft dt 30lk is a 2 to 200000rpm tachometer that has been designed to measure and display rotation speed and belt speed the given measurements are either non contact via the built in laser or per direct contact using the included adaptors p p the rotation speed can be displayed in rpm revolutions per minute hz m min in min ft min and yd min the product can also display the total number of revolutions during m