The exclusive X-Ring D.I.D at the top of technology Reduced power loss (compared to standard O-rings) Friction performance: By twisting but not squeezing, the shape of the exclusive X-Ring D.I.D reduces friction between the plates Durability performance: The shape of the exclusive X-Ring D.I.D is designed to ensure better sealing of the grease inside the chain and its protection against water and dust. This allows better performance and longer life