Check the listing for details. Spring Joint Caliper 300mm Adjustable Spring Inside Caliper with Solid Nut. Condition: New. Listed at 18.09 USD. Size - 325mm length x 325mm width spring joint inside caliper with a max open length (capacity) of 12 inch / 300mm.Material - Our metal calipers are forged from stainless iron, with overall heat treatment, wear resistance, durable and long service life.Feature - The forged high-carbon steel legs feature hardened points for precise marking of the workpiece and precise fine adjustment by opening and closing the legs by means of an adjusting nut.Application - Inside caliper is a useful measurement transfer tool for measuring the inner diameter or groove width of the cylindrical hole, and then transferring that measurement to a ruler.Usage - Smooth surface and burr-free, accurate measurement, can be used for a long time and not easy to loosen.