1. Three Basic Dimensions
Pitch, Roller Diameter and Inner Width are referred to as the “Three Basic Sizes of Roller Chain.” When these three dimensions are identical, roller chains and sprockets are dimensionally compatible.
2. Basic Parts
Link Plate
The plate is the component that bears the strain placed on the chain. Usually this is a repeated loading, occasionally accompanied by shock. As a result, the plate must not only have got great static tensile strength, it must also hold up to the powerful forces of load and shock.
Pin
The pin is subject to shearing and bending forces transmitted by the plate. At the same time, it forms a load-bearing part (alongside the bush) when the chain flexes during sprocket engagement. Therefore, the pin needs high tensile and shear strength, level of resistance to bending, and must have sufficient endurance against shock and put on.
Bush
The bush is subject to complex forces from all parts, especially from the repetition of shock loads when the chain engages the sprocket. Therefore, the bush needs incredibly high shock resistance. Furthermore, the bush forms a load-bearing part together with the pin and therefore requires great wear level of resistance.
Roller
The roller is at the mercy of impact load as it mates with the sprocket teeth during 
engagement of the chain with the sprocket. After engagement, the roller changes its point of contact and stability. It is held between the sprocket tooth and bush, and moves on the tooth encounter while getting a compression load. For that reason, it should be agricultural Chain resistant to use and still have power against shock, exhaustion and compression. (RS25 and RS35 are bush chains and do not have rollers).
Roller Link
Two bushes are press fit into two roller hyperlink plates and rollers are inserted to permit rotation around the exterior of the bushes during operation. This is actually the same for solitary and for multi strand chains.
Pin Hyperlink and Intermediate Plate
The pin link consists of two pins which have been press match two pin link plates. In case of multi-strand roller chain up till size 08B, an intermediate plate is put into the pin hyperlink. In the event of multistrand roller chain above size 08B, two intermediate plates are put into the pin hyperlink. The intermediate plates are slip fit for regular roller chain and press match for Extremely roller chain.