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
O-Ring Sizes - Metric - Complete Gasket Solutions
Measure Diameter Ring | Gaskets Ring Gasket | Ring Measuring Tool | Ring Measurement - Gaskets - Aliexpress
887-300 - Parker® - O-Ring Sizing Kit - O Ring Sizing Cone - Yellow