1. Three Basic Dimensions
Pitch, Roller Diameter and Inner Width are referred to as the “Three Basic Dimensions of Roller Chain.” When these three sizes are similar, roller chains and sprockets are dimensionally compatible.
2. Basic Parts
Link Plate
The plate may be the component that bears the strain placed on the chain. Usually this is a repeated loading, sometimes accompanied by shock. As a result, the plate must not only have great static tensile strength, it must also endure to the dynamic 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 (together with 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 also have sufficient stamina 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. Consequently, the bush needs incredibly high shock resistance. In addition, the bush forms a load-bearing part together with the pin and therefore requires great wear level of resistance.
Roller
The roller is subject to 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 your sprocket the teeth and bush, and progresses the tooth face while receiving a compression load. Consequently, it must be resistant to wear and still have power against shock, Leaf Chain fatigue and compression. (RS25 and RS35 are bush chains and don't have rollers).
Roller Link
Two bushes are press fit into two roller hyperlink plates and rollers are inserted to permit rotation around the outside of the bushes during operation. This is actually the same for one and for multi strand chains.
Pin Hyperlink and Intermediate Plate
The pin link contains two pins that have been press match two pin hyperlink plates. In the event of multi-strand roller chain up till size 08B, an intermediate plate is certainly added to the pin link. In the event of multistrand roller chain above size 08B, two intermediate plates are put into the pin hyperlink. The intermediate plates are slide fit for standard roller chain and press fit for Extremely roller chain.