Waterway 2" Split Heater Union w/Screws
To establish the correct size measure the inside diameter "ID" of your current "closed" split nut or regular nut.
If it measures:- 2-7/16" then you need a 1-1/2"
- 3-1/16" then you need a 2"
- 3-11/16" then you need a 2-1/2"