New designed dial movement for ultra smooth sliding and high shock protection. Titanium Nitride (TiN) coating is applied to the sliding surface to increase wear resistance(except for 0-300mm and 0-12" model). Can measure OD, ID, depth, and steps. Lock screw for dial bezel and for holding the slding jaw position . Models available with carbide-tipped OD and ID jaws. Supplied in fitted plastic case.