Machine tool bearings are precision angular contact bearings, non-separable with outer ring relieved and available with 15† or 25† contact angles. These bearings, for critical applications, are stocked as universally ground duplex pairs with standard preloads and as single row bearings. A separate design for a separable, single row bearing series with inner ring relieved and 15† contact angle is also available. Duplex pairs can be mounted backto-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. These bearings are employed in a variety of machine tool equipment for grinding, turning, milling, routing, drilling and threading applications.