Who else would you trust for aftermarket upgrade parts for your DM than Billy Wing. Billy is a 12 year Pro veteran, and one of the head designers of DYEí?s extensive gun line. The B-Wing bolt kit is hand polished and fitted to ensure pro level performance. The mirror like finish allows for a lower LPR pressure, which renders less kick. The B-Wing bolt also helps prevent bolt stick, which improves shot to shot consistency. Compatible with the̴Ì_DM14 and DM15.