O-Ring Gauge Make Work Smart, Telescoping O Ring Sizing Plastic Gauge, Slide Style National Type, for Measuring O Rings Inner Diameter, OD, Thickness Gauge Black: Amazon.com: Industrial & Scientific
Parker - O Ring Sizing Cone - 65062994 - MSC Industrial Supply
PLSTC SIZING CONE TOOL O RING MEASURING CONE ONE SET - Sin Thye Loke Oil Seals Sdn Bhd
O-ring Gauge Slide Type National Sizing Measure Plastic Blue Oring Gauge For As568 & Bs 1806 Range - Oil Seals & Other Seals - AliExpress
How to Measure an O-Ring - O-Ring Slide Gauge - YouTube