This part is an Air Check Valve with a 1" Slip Fittings on one end. This valve is used above the water line to allow constant air flow in one direct and to stop water flow in the other direction when plumbed properly in a Hot Tub.
This type Check Valve is used in a system where the tub has not Air Control valve these just allow air to be pulled through the venturi effect any time that the pump is running and pushing water through that system of jets. In some applications you will need another part that glues inside of this valve to connect 3/8" air lines. Links to those are below..
Adapters for this valve:
Note: You will need glue to do this repair: PVC Red Hot Blue Glue Christy's 4oz for Hot Tub Spa PCV Plumbing Repair Video
Manifold, 3/8"sb, 2 Port, Transition, 1"spg
Manifold, 3/8"sb, 4 Port, Transition, 1"spg
