Features1Aluminum Alloy: The aluminum alloy bottom bracket shell is made of aluminum alloy material, which is sturdy and durable. 2Silicone Sealing Ring: A double silicone sealing ring is installed at the port at the bottom of the bracket. 3Long Service Life: Prevent pollution, prolong service life, and easy to install, alloy material, durable and long service life. 4Protect the Frame: The threaded system can protect the frame and output more power, better than the ordinary structure. 5Specifications: The outer diameter of the bicycle bottom bracket is 47mm, the inner diameter is 30mm, five way for built in 86/92mm.SpecificationItem Type: Bicycle Bottom BracketMaterial: Aluminum AlloyOuter Diameter: Approx. 47mm / 1.85inInner Diameter: Approx. 30mm / 1.18inFive Way: Built in Approx. 86/92mmPackage List1 x Bicycle Bottom Bracket