Cylindrical roller bearings consist of a robust outer race, inner race, rollers and a cage. Outer races either feature bilateral collars, or no collar at all. Inner races come in different types:Single-row:· N = two collars on inner race, no collar on outer race· NU = no collars on inner race· NJ = one collar on inner race· NUP = inner race with 1 collar, 1 free-moving separatorDouble-row:· NN = double row cylindrical roller bearing· NNU = double row cylindrical roller bearingThe cage prevents the moving rollers touching each other. Cylindrical roller bearings are extremely robust, able to cope with high radial load. Moreover, the cage enables movement at high speed. The bearings can be dissaasembled which makes both fitting and taking them out easier. This also enables optimum fitting of inner and outer race.Postposed characters are used to identify different bearing types.· C3, C4 = clearance rating· E = reinforced· EX = reinforced· M1 = two-part brass cage, roller guidance· M1A = gu