R-Hop is the single most important part in airsoft that extends your effective range to over 60m/200ft. Max range of 90m/300ft can be achieved (with M130 spring, 1.7J). Package includes: R-Hopped ZCI 6.02mm Tightbore Barrel. An extra R-Hop, Modify Baton Flat-Hop Bucking. This R-Hop is Extremely hard to fabricate due to the 2X 95 degree cuttings. 7 Lengths to choose from: 300mm, 340mm, 363mm, 380mm, 407mm, 455mm & 509mm. Traditional R-Hops are 1.5mm thick and airsoft barrels are 1.25mm thick. Thus, sanding is required. Our R-Hops are Exactly 1.25mm thick. Therefore, NO SANDING is required.