Copper 10w3 Square Bar is a copper-tungsten alloy containing around 25% tungsten and 75% copper. It combines the wear and arc-erosion resistance of tungsten with the high electrical and thermal conductivity of copper. This rectangular bar shape is well-suited for applications like electrical discharge machining electrodes, welding dies, and projection welding electrodes where its unique blend of hardness, conductivity, and wear resistance are beneficial.