On race day, everything - every loose flap of clothing, every calorie taken in, and every watt put out - matters. For those looking for extra speed beyond our stock top grade steel bearings, Zipp is proud to introduce new hybrid ceramic bearings for the 77/77D and 177/177D hub, produced in partnership with CeramicSpeed?. With measurable savings of 1.5-9 watts, they´re the ultimate complement to the race proven speed of Firecrest® wheels.- Lowest resistance hybrid ceramic (ceramic balls and steel races) available- Measurable wattage savings between 1.5 and 9 watts per bearing set, depending on the level and condition of your existing bearings- Available in convenient two-packs for Zipp 77/77D front hubs and 177/177D rear hubs (177 freehub uses same kit as 77 hub)