If the bearing is mounted at the end of a shaft i.e. not a through-shaft, the bore at the outer side of the housing should be closed by means of a cover.

These end covers, which are supplied separately in packages, are designated ASNA followed by the number of the housing, for example ASNA 506-605.

Plummer blocks of the series most frequently used, SNA 5 and SNA 6, are available with a seal set comprising one end cover and one 'V'-ring seal and are then given the suffix ATA, for example SNA 505 ATA.