This CNC Aluminum version 2 one-piece hop up from SHS makes a superior replacement for most standard V2 hop ups. The rotary wheel makes for easier adjustment than the standard 3-gear system especially when used with gloves. Twin Self-Stabilizing Pistons greatly reduce overall impacts to prolong the lifespan on the hop-up unit. This package includes the hop-up unit, bucking, C-clip, brass ring, and SHS red bucking; everything you need for a quick and seamless installation! Using hop-up puts spin on the BB after it leaves the muzzle, making it very easy to adjust for various BB weights and target ranges.