More informationRollerBoys 12T srRollerBoys, the 12x12T CrMo derailleur pulleys. Manufactured in high-performance composite material by EMS Swiss, they are composed of 40% fiberglass. This makes our RollerBoys durable and efficient. With sealed bearings protected by an aluminum cover, these pulleys guarantee optimum long-term performance. RollerBoys integrate perfectly with SRAM 12-speed road groupsets, guaranteeing a smooth, precise cycling experience.12x12T CrMo derailleur pulley.High-performance composite material from EMS Swiss with 40% fiberglass.Sealed bearings with aluminum cover for optimum durability.Compatible with SRAM 12-speed road groupsets.