Prime PF30 Bottom BracketPrime's PF30 Bottom Bracket packs a lot of technology into a compact package to keep your cranks running smoother for longer. At Prime we use the best elements from different materials to ensure optimum performance.Creak-Free Bottom BracketThe bearings are held in place by an alloy cup, but in order to keep the BB and frame quiet and creak-free, they are housed in a plastic/nylon shell. Finding the right mix of plastic and nylon has allowed us to precisely manufacture these BBs so they won't deform over time or when they get wet. It also allows the BB to fit in frames that aren't perfectly aligned.Our bearings inside our PF30 BBs are precisely manufactured to spin smoothly, and when combined with our special seals, repel the elements. The seal is made from a mix of rubber and alloy to provide double protection for the bearings. And, we hand assemble these bottom brackets to ensure none of this development and precision is wasted.Ceramic Bearingsthey're also more durable, and don't rust so they'll require less maintenance. If you're a rider seeking out every possible advantage over the competition, the ceramic option can help take your performance to the next level.Features: Bearing: Premium Stainless Steel & Ceramic options available Frame Type: PF30 Crank Type: SRAM (30mm) or Shimano/FSA (24mm) when used with the Prime Bottom Bracket Adaptor (PF30 - Shimano) Weight: 92g (Steel Bearings), 87g (Ceramic Bearings)Buy Prime Components from Chain Reaction Cycles, the World's Largest Online Bike Store.