This parts is an Upgraded Starfire Style 4" Starfire Black Knob Only. 

The Valve this part fits is found on Newer Cal Spa but will fit many other brands too. 

Compare the measurements to be sure this is correct. 

This listing is for the Knob only all other parts shown are for illustration only but we offer them in our store.

For more information on this cap and the difficulties of repairing and how to Install please see our video on youtube search for : "Cal Spa Diverter Leak The Spa Guy How To Series"