There are actually two types of links alternating in the bush roller chain. The 1st type is internal links, having two internal plates held together by two sleeves or bushings where rotate two rollers. Inner links alternate with the next type, the outer links, consisting of two outer plates held with each other by pins moving through the bushings of the internal links. The “bushingless” roller chain is similar in operation though not in construction; instead of individual bushings or sleeves keeping the inner plates together, the plate has a tube stamped involved with it protruding from the hole which serves the same purpose. This has the advantage of removing one part of assembly of the chain.
The roller chain design reduces friction compared to simpler designs, leading 
to higher efficiency and less wear. The initial power transmission chain types lacked rollers and bushings, with both inner and external plates kept by pins which straight contacted the sprocket the teeth; however this configuration exhibited incredibly rapid use of both the sprocket the teeth, and the plates where they pivoted on the pins. This issue was partially solved by the advancement of bushed chains, with the pins holding the outer plates moving through bushings or sleeves connecting the inner plates. This distributed the use over a larger area; however the teeth of the sprockets still wore quicker than is attractive, from the sliding friction against the bushings. The addition of rollers surrounding the bushing sleeves of the chain and provided rolling contact with one’s teeth of the sprockets leading to excellent resistance to use of both sprockets and chain Stainless Steel Chain aswell. There is even very low friction, so long as the chain can be sufficiently lubricated. Continuous, clean, lubrication of roller chains is definitely of primary importance for efficient procedure in addition to correct tensioning
