For GBB/VSR10 spec inner barrel and without modify (Marui / WE / VSR-10)Larger & wider contact area inside of BB pellet, has better hop effect with heavy BBFor Heavy BB pellet onlyThe “Shield” shape groove design has better hop effect when tensioner/lever press itRetain the steel “C-ring” design for airseal from “Transformer HOP”seriesThe R-hop Rubber kit begin from a small group user who want to increase the range and hop effect of heavy bb.The title “R” mean the “RANGE”. But it need modify the original AEG hop rubber and stick the rubber patch by user self,
