Bush is a plain bearing surface made of a comparatively softer metal that is inserted into a housing to provide a bearing surface for rotary part in variety of applications. Since most rotating parts like shafts are made of steel, bushes or plain bearing is made of alloys viz brass and bronze which have excellent wear properties. Gunmetal is an alloy that is known for its robustness, heat resistance and anti-corrosive property.

Gunmetal is an alloy of copper, tin and zinc also known as bronze, which casts and machines well and is resistant to corrosion from steam and salt water and therefore it, is used to make steam and hydraulic castings, valves, gears, statues, and various small objects. There are several types of bush bearings viz brass, bronze, self-lubricated oil, graphite etc.