The ends of both contact are head treated stainless steel and precision ground to a radius to allow proper clearance on the smallest hole the gage will enter
Constant spring tension gives uniform contact pressure
Handles are rigidly attached to the contact plungers and are automatically self-centering
Nickel-plated finished
Double action rigid handle with self centering feature for quick checking of holes, slots and recess up to 6" deep

Usage:
Under uniform spring tension, the plunger of the gage expand from the center to the diameter of the hole or width of slot being measured and then locked in place by a knurled knob,
the hole size is found by measuring over the two contact point with a micrometer or caliper.

Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/-1-3cm.