【Range】5/16" - 6" (8mm to 150mm), Stainless Steel Construction.
【Using】This bore gauge expands in a hole to be measured , locks in place and then removed to determine final hole size using a micrometer or calipers. It is suitable for measuring the inner diameter of holes, such as the inside of cylinders and bores of engines.
【Package】Includes 6 sets, with vinyl case
【Fine Workmanship】The contact point of this machinist tool is hardened tool steel and is fine ground within the final measuring radius
【Smooth and constant spring tension】 The spring is equipped with a knurled locking knob and a knurled fixing area.