O Ring and X Ring Chains Whats the different?

[Mr C]

Just wondering what the difference is as im going to buy new C&S.

[nelly]

O and X denote the cross section of the sealing ring that sits inside the side plates over the rivet.
The O profile essentially gives a single point of contact with which to seal against the plate.
The X section gives 2 points of conatct so is considered the more durable.
I'd go X ring every time.