DID is original equipment manufacturer of many Japanese and European brands. Leading racing teams in the Road and off road sports rely on the technology of DID. DID 520ERVT: The 520ERVT is a particularly slim X-ring chain for use in enduro racing. Due to the slim design, it can often be used in Enduro Racing models, have the tight space and factory-equipped with chains without sealing ring. The low friction of the patented X-rings also reduces the power loss in the drive train and is a guarantee of high wear resistance. -High wear resistance through patented X-ring technology - slim design