HydroAir Hi Volume suction cover to fit Hi Volume wall fitting. 

This suction cover is part of the HydroAir / Balboa Standard suction. 

The grille is an important safety device, as it prevents the possibility that a swimmer may get stuck against the suction point by the force of the pump. If a grate breaks, it must be replaced immediately.

The central screw thread, which is part of the suction cover, allows it to be fixed on a wall fitting in standard or long version depending on your installation.