Very common jet diverter used on spas since 2004. Suits Waterway 2" Diverter valves after 2004. Will have the word ' BUTTRESS' stamped in the mould on the underside. There is a similar Hydroair diverter listed here.
Approx 95mm diameter, 12mm thread height, cap thread diameter 70mm ID.
If your diverter cap has the word "BUTTRESS" under the top, these do not fit. Please go here.