Spaquip 40mm threaded, 50mm Spg x 40mm Skt Heater Tee Male Tail Union Body

Spaquip / Davey 'male tail' threaded union section with 50mm/2" spigot 

The 2" spigot allows gluing 50mm/2" fittings such as alternate heater tails, elbows and couplings over the outside of it

Thread size is 50mm union size (79mm OD)
This is a specialty component 
This component is used  to convert a 50mm heater union to barrel union for replacement of a dis-similar heater without cutting original heater unions from the plumbing
Can also be used on certain pump unions
Suits replacement of existing heater - Spa Power 600, 601, 800, 1200
Suits replacement plumbing of existing pump - Maxiflow, Monster