Chesapeake White SS 2" Hourmeter (10,000 Hrs) (12-32 VDC)2" - Hole size: 2.0625" (53mm)Hourmeter operates by applying battery voltage across the gauges's register motor to ground. The register increments increase when the key switch in on. Route power through a normally open Oil Pressure switch to count "engine running" hours.Benefits:0-10,000 HoursEngine Running only