CE-2500N Hardness Tester for Metals Portable handheld pen-sized durometer for use with steel, iron, aluminum, brass, bronze, copper and more. PCE-2500N is a portable handheld pen-sized digital material hardness tester, rebound hammer or durometer for use with metals. This high-accuracy hardness tester quickly and accurately measures the surface hardness of 10 common metal materials including steel, cast steel, alloy tool steel, stainless steel, cast iron, ductile iron, cast aluminum alloy, brass, bronze and copper.