STKUSA Telescopic Gauges Caliper 5/16" - 6", 6-Piece Double action rigid handle with self centering feature for quick checking of holes, slots and recess up to 6" deep 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 1 gage: 5/16 - 1/2" range x 4.20"; 1 gage: 1/2 - 3/4" range x 4.40"; 1 gage: 3/4 - 1-1/4" range x 4.40"; 1 gage: 1-1/4 - 2-1/8" range x 5.85"; 1 gage: 2-1/8 - 3-1/2" range x 5.85"; 1 gage: 3-1/2 - 6" range x 5.85"