DID is an OEM of many Japanese and European brands. Leading racing teams in the Road and off-road sports rely on the technology of DID. DID 420D: As a successor to the tried and tested 420 standard chain, the 420D used a new technology for manufacturing the rollers. Up to now, the rolls of sheet metal strips have been wound, resulting in a seam and thus a weak point. Thanks to the new technology, the rolls are made of round material and a sewing area is thus avoided. - 20-50% higher wear resistance compared to DID 420