Radius gauge

[2] Radius gauges require a bright light behind the object to be measured.

The gauge is placed against the edge to be checked and any light leakage between the blade and edge indicates a mismatch that requires correction.

[3] A good set of gauges will offer both convex and concave sections, and allow for their application in awkward locations.

[4] The material of the leaves is stainless steel.

Each gauge is one of two types; either internal or external, which are used to check the radius of inner and outer surfaces, respectively.