There are two types of links alternating in the bush roller chain. The initial type is internal links, having two internal Stainless Steel Chain plates held jointly by two sleeves or bushings upon which rotate two rollers. Internal links alternate with the second type, the outer links, comprising two external plates held together by pins moving through the bushings of the internal links. The “bushingless” roller chain is similar in operation though not in structure; instead of individual bushings or sleeves holding the inner plates with each other, the plate includes a tube stamped into it protruding from the hole which serves the same purpose. This has the benefit of removing one step in assembly of 
the chain.
The roller chain design reduces friction in comparison to simpler designs, resulting in higher efficiency and less wear. The initial power transmission chain varieties lacked rollers and bushings, with both inner and external plates kept by pins which directly contacted the sprocket the teeth; however this configuration exhibited incredibly rapid wear of both the sprocket teeth, and the plates where they pivoted on the pins. This problem was partially solved by the advancement of bushed chains, with the pins holding the outer plates passing through bushings or sleeves connecting the inner plates. This distributed the use over a larger area; however the tooth of the sprockets still wore more rapidly than is desirable, from the sliding friction against the bushings. The addition of rollers surrounding the bushing sleeves of the chain and offered rolling contact with one’s teeth of the sprockets resulting in excellent resistance to wear of both sprockets and chain aswell. There is even suprisingly low friction, provided that the chain is sufficiently lubricated. Constant, clean, lubrication of roller chains is certainly of primary importance for efficient operation in addition to correct tensioning