The most popular sizes of deep groove ball bearings are also produced in sealed versions with shields or contact seals on one or both sides. Details about the suitability of the different seals for various operating conditions can be found in table . Sealed bearings in the 622, 623 and 630 wide series () are particularly suitable for long maintenance-free service. In addition, ICOS bearing units with integrated radial shaft seals are available for higher sealing requirements.