Pump Barrel Union that suits several brands and styles of pumps and heaters. 

Suits the following:
LX JA35 & JA50
SpaNET XS-3c
Aqua-flo CircMaster CMCP & CMHP
Edgetec Triflo & other Edgetec pumps
ITT Laing Thermotech E-14

And many many more. Does not suit Davey XB, or Onga / Balboa Bathmaster