The durability kit includes our best-selling ceramic oversized derailleur cage, ceramic bottom bracket, and a full maintenance kit to keep your drivetrain spinning like new for years to come! Unlock untapped speed. Experience silky smooth pedaling, seamless shifting and 100% power transfer with each pedal stroke. Ceramic Oversized Derailleur Cage: Improves rolling resistance, shifting accuracy, and power transfer. Ceramic Bottom Bracket : Extremely reliable and efficient bottom brackets that increase bottom bracket stiffness. Maintenance Kit : Pulley service kit with a set of 4 seals and a syringe of our low friction grease. "Gain Chain" Wax-Coated Chain : Our wax-coated chain improves drivetrain efficiency over a standard lube chain. *After placing an order, our team will work with you to configure your kit and determine the right parts for your bike.