Thread Check Inc. offers trilock plug gages in class XX thru ZZ gagemaker tolerances for checking large diameter holes. Like reversible gages, when one side wears out, the gage can be turned around. This design significantly increases the life of the gage. Trilock plug gages are made of quality tool steel for longer gage life. Sizes range from 19.30mm ‐ 203.45mm. The trilock handle has three prongs on the ends which fit into three grooves equally spaced around the central hole of the gage members. A bolt holds the member to the handle and the trilock grooves and prongs stabilize the gage member.