Cylindrical roller bearings are characterized by high radial-, and moderate thrust-load capacities.  They contain cylindrically-shaped roller, which are nevertheless not true cylinders. Instead, they are crowned or end-relieved to reduce stress concentrations. This particular geometry results in low friction and allows high-speed applications. Cylindrical roller bearings are commonly available in precision grades such as RBEC-5, a classification from the Roller Bearing Engineers Committee (RBEC). RBEC ratings describe the accuracy and tolerance range of different types of bearings. As a rule, the higher the RBEC number, the tighter the bearing tolerances. Typically, cylindrical roller bearings are lubricated with oil, which also serves as a coolant.