Spindle & Precision Machine Tool Angular Contact Bearings, non-separable with outer rings relieved and available with 15° or 25° contact angles. For critical applications these bearings are stocked as universally ground duplex pairs with standard preloads and as single row bearings. A different design for separable, single row bearing series with inner ring relieved and 15° contact angle is also available. Duplex pairs can be mounted back-to-back, face-to-face or tandem depending on the loading expected. Due to high speeds, these bearings usually require phenolic retainers, which have either a stepped or cylindrical pocket design.