This listing is for 4 piece/s.A bushing is also known as a bush is an independent plain bearing inserted into a housing to provide a bearing surface for rotary applications. This is the common form of a plain bearing. The common designs would include split, solid and clenched bushings. They are only a sleeve of material with an inner diameter, length and outer diameter They also help to constrain and restrain the motion of the parts. Sometimes, they are also known as a plain bearing. Bushings are used to line holes in stationary parts of a mechanism. They are particularly effective in spreading friction and wearing over the surface of the bushing as opposed to directing into a single spot. The main advantage of a bushing, as compared to a solid connection, is less noise and vibration are transmitted. Another advantage is that they require little to no lubrication. Specifications Inner Diameter: 20mm Outer Diameter: 28mm Width: 25mm