RWC aluminum cups precisions machined in the USA with Enduro 440C Stainless Steel Angular Contact ABEC 5 Bearings. Fits standard "BSA" threaded bottom bracket shells using Left and Right cups. With the right cranks, can also be used on 100mm and 120mm FATBIKES. Not all BB30 cranks are compatible due to varying spindle lengths. Some of the cranksets known to be compatible include:

e13 Mountain Cranks Race Face Next SL cranks Race Face SIXC Cinch Race Face Turbine Cinch Rotor 3D+ cranks BB386 EVO Road Cranks Cane Creek eeWings MTB cranks

Angular contact bearings are a step forward in outboard bottom bracket design. Why? Deep groove radial ball bearing cartridges are not designed to be "adjusted." Any inward or outward pressure on the inner races put them out of alignment with the outer races, forcing the balls to ride up the side of the groove and exerting greater pressure on the races. This results in increased friction and premature wear. Since almost all outboad crank sets exert some inward pressure on the bearings when installed, it only makes sense to use a bearing designed specifically for such loads. Angular contact bearings result in 100% ball engagement when properly pre-loaded.