X-ring chain

It has higher performance (in terms of durability, lifetime, and power loss) than non-O-ring chains as it has less friction than O-ring chain while providing adequate lubrication and protection against foreign elements which also increases reliability.

Therefore, X-ring chain was developed by replacing O-ring seal with X-ring seal which greatly reduced friction and increased durability.

[1] Like the O-ring chain it has sealing rings which keep the contaminant (dirt) out, and lubricant in between the pins and bushings.

However, unlike O-ring chain, it has X-shaped seal which does not experience increased surface area (which is in contact with the chain plates) when under pressure.

Due to their unique shape, they have two additional sealing surfaces to a traditional O-ring.

Difference between X-ring and O-ring chains.
Difference between X-ring and regular O-ring chains. The seals are red in color.