Roller chain or bush roller chain is the kind of chain drive mostly used for transmitting of mechanical power on many types of domestic, commercial and agricultural machinery, including conveyors, wire- and tube-drawing devices, printing presses, vehicles, motorcycles, and bicycles. It 
consists of a series of short cylindrical rollers held with each other by aspect links. It is powered by a toothed wheel called a sprocket. It really is a simple, reliable, and efficient[1] method of power transmission.
Though Hans Renold is credited with inventing the roller chain in 1880, sketches by Drive Chain Leonardo da Vinci in the 16th century show a chain with a roller bearing.