New hi quality MADE IN ITALY product Crafted by the hi tech GRIZZLY technicians and ready to take wide part of Italian and European market!! Made of hard OT63 and finished with diamond process machine to made the surface as smooth as possible.... hi precision and flawless inner diameter of 6,01mm for Marui, G&G, G&P, VFC aeg and compatibles due to the barrel size please use only hi quality and not reused bbs