BOX Four Prime 9 Derailleur(8spd) Wide Cage - BlackPrime 9 Technology for less derailleur travel and better chainline. Less wear and improved lifespan Box One features: Adjustable Tri Pack limited slip clutch, forged inner and outer cage, Pivot Tech cable stay, sealed bearing pulleys and 3D forged linkages Box Two features: Tri Pack limited slip clutch, forged inner and outer cage, Pivot Tech cable stay, sealed bushing pulleys and 3D forged linkages Box Three features: Limited Slip Clutch, stamped