Taking inspiration from off-road racing, the Factory Race Series rear upgrade kit for the Gen 2 Raptor utilizes the same technology and parts found on the top race-winning off-road machines, including External Bypass position-sensitive damping, Quick Adjust Bypass (QAB), and an External Cooling System (ECS2).This kit delivers the next level of off-road performance without sacrificing every day ride quality. Position-sensitive External Bypass damping technology features 4 adjustable bypass zones Quick Adjust Bypass (QAB) adjusters allow tool-free bypass zone adjustment Race-developed External Cooling System (ECS2) provides increased cooling efficiency Internal & external aluminum fins increase cooling surface area & heat dissipation Forced, unidirectional fluid circulation maximizes cooling efficiency ECS2 mounting hardware included Steel External Bypass body with a new, proprietary coating for improved durability Anodized aluminum piggyback reservoir and cooler resists corrosion and helps dissipates heat 7/8” hard chrome plated 17-4 H900 stainless steel shafts Hard anodized 6061-T6 billet aluminum high flow race piston Heat treated steel spherical heim mounting