The performance upgrade for drivetrains with outboard bottom brackets. Replace your existing BB bearings with performance Zero Ceramic bearings. Proven time and again in World Cup race conditions, the ZERO Ceramic bearings are the ultimate race day weapon. Oversized Grade 3 balls roll on races which are ground to a mirror finish after receiving Magnetite and then Cryogenic treatments for hardness and longevity. More durable and with even lower rolling resistance than any 2RS bearings, they come closer to that magic ?zero rolling resistance number. Enduro Bearings uses Silicone seals which are more slippery than rubber seals used by other ceramic bearing suppliers.Kit includes complete set of Zero Ceramic bearings and sealsCompatible with Shimano and Race Face outboard bottom brackets42.48g