Maple Leaf AST ESD EVO II Hop-Up Set Inner Barrel for KWA / KSC USP COMPACT GBB ( EVO 2 ) - New Design Hop-up for KWA / KSC USP GBB Pistol Series - Impressive accuracy - Extremly effective firing range extend. - 6.01mm inner barrel and Monster Hop-up rubber included. - Length: 80mm