1. Three Basic Dimensions
Pitch, Roller Diameter and Inner Width are known as the “Three Basic Measurements of Roller Chain.” When these three sizes are similar, roller chains and sprockets are dimensionally compatible.
2. Basic Parts
Link Plate
The plate is the component that bears the tension positioned on the chain. Usually this is a repeated loading, occasionally accompanied by shock. 
Therefore, the plate should never only have great static tensile power, it must also hold up to the powerful forces of load and shock.
Pin
The pin is at the mercy of shearing and bending forces transmitted by the plate. Simultaneously, it forms a load-bearing part (together with the bush) when the chain flexes during sprocket engagement. Therefore, the pin requirements high tensile and shear strength, level of resistance to bending, and must also have sufficient Drive Chain endurance against shock and wear.
Bush
The bush is subject to complex forces from all parts, especially from the repetition of shock loads when the chain engages the sprocket. As a result, the bush needs incredibly high shock resistance. In addition, the bush forms a load-bearing part together with the pin and as such 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 progresses the tooth face while getting a compression load. For that reason, it should be resistant to use and still have power against shock, exhaustion and compression. (RS25 and RS35 are bush chains , nor have rollers).
Roller Link
Two bushes are press match two roller link plates and rollers are inserted to permit rotation around the exterior 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 consists of two pins which have been press fit into two pin link plates. In case of multi-strand roller chain up till size 08B, an intermediate plate can be added to the pin hyperlink. In the event of multistrand roller chain above size 08B, two intermediate plates are added to the pin link. The intermediate plates are slide fit for regular roller chain and press suit for Extremely roller chain.