Go/No-Go gaging is an inexpensive but, very accurate measurement of hole diameter. Go/No-Go plug gage assemblies consist of a Go gage pin, No-Go gage pin, handle & 2 bushings. The Go gage pin, (tolerance plus) represents the minimum size of the hole to be measured. The No-Go gage pin, (tolerance minus) represents the maximum size of the hole to be measured. The hole is considered in tolerance if the Go goes into the hole & the No-Go does not.