AIMILAR LCD Digital Inductive Tach Hour Meter Tachometer for 2 Stroke Gas Engine Motorcycle Marine Black This tachometer hour meter works on 2 stroke gas engine, hour glass symbol appears and flashes on/off to indicate counting time Has the same features as hour meter plus tachometer feature. No Battery Required-connects to spark plug wire. Indicates operation in RPMs and hours.Maximum RPMs 15300 rpm, Maximum Hours: 99999.9 Easy Installation no power or ground required.