Conventional air gaging for measuring inside diameters is typically limited to a minimum size of about 0.060"/1.52mm: below that, it becomes difficult to machine air passages in the plug tooling, and to accommodate the precision orifices or jets. But air gaging is among the most flexible of inspection methods, and with a simple change of approach, it can be used to measure very small through holes, below 0.040"/1mm in diameter.