Diverter Plate for use with a Waterway Dyno-Flo T/M Skim Filter (QF code: 6371 / MPN:500-8047 )
This diffuser plate should sit directly above the filter, blocking the top opening, and underneath the skimmer basket.
It has slots in the top side, which match the moulded feet of the basket, so that the basket and the plate clip together.
They are often glued together in practice.
This plate is used with several models of Waterway skimmer basket, including the Lo-Profile basket.