There are two types of links alternating in the bush roller chain. The 1st type is inner links, having two internal plates held jointly by two sleeves or bushings where rotate two rollers. Internal links alternate with the second type, the outer links, comprising two external plates held collectively by pins moving through the bushings of the inner links. The “bushingless” roller chain is comparable in operation though not in construction; instead of separate bushings or sleeves keeping the inner plates with each other, the plate has a tube stamped into it protruding from the hole which serves the same purpose. It has the Stainless Steel Chain 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 original power transmission chain types lacked rollers and bushings, 
with both inner and outer plates kept by pins which straight contacted the sprocket tooth; nevertheless this configuration exhibited incredibly rapid put on of both 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 linking the inner plates. This distributed the put on over a greater area; however the teeth of the sprockets still wore quicker than is appealing, from the sliding friction against the bushings. The addition of rollers encircling the bushing sleeves of the chain and offered rolling contact with one’s teeth of the sprockets leading to excellent resistance to wear of both sprockets and chain aswell. There is even very low friction, as long as the chain is sufficiently lubricated. Continuous, clean, lubrication of roller chains is usually of major importance for efficient operation as well as correct tensioning.