Markon standard 3 notch scalloped top draw chrome spa bath air venturi control. Common on Caroma, Stylus, Lanark, Decina, Englefield, Kohler and many others.
46mm diameter top
Suits 32mm diameter hole in spa bath
Plumbing connection:
1. 0.5″ / 15mm socket – suits 15mm pipe
2. 0.75″ / 20mm spigot – suits 20mm fittings, or Markon 2 barb adaptor