Thread-together bottom brackets provide a secure and stable shell interface for smoother operation and extended bearing life Hybrid AL6061/Nylon fiber cups for a superior fit and noise-free operation Low-friction dual seals protect the bearings from harmful contaminants Sealed premium bearings are both serviceable and replaceable Designed for installing Shimano HTII 24mm or SRAM GXP 22/24mm spindle cranks into BB30 frames without the need for adapters Origin8 Nylon composite BB tools are recommended to avoid the possibility of damaging the cups 68/73mm x 42mm BB30 Shimano HTII 24mm AL6061/Nylon Fiber 123g