Cylindrical roller bearings consist of a robust outer race, inner race, rollers, and a cage. Outer races may feature bilateral collars or no collar at all. Inner races come in different types:

Single-row:

• N = two collars on the inner race, no collar on the outer race.
• NU = no collars on the inner race.
• NJ = one collar on the inner race.
• NUP = inner race with one collar and one free-moving separator.

Double-row:

• NN = double row cylindrical roller bearing.
• NNU = double row cylindrical roller bearing.

The cage prevents the moving rollers from touching each other. Cylindrical roller bearings are extremely robust and can cope with high radial loads. Furthermore, the cage enables movement at high speeds. The bearings can be disassembled, which makes both fitting and removal easier. This also allows for optimum fitting of the inner and outer races. 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 = guidance on the outer ring.
• TVP2 = robust PVC cage.
• JP3 = sheet metal cage.