Once the jet is plumbed and gunited into the spa, the internals are interchangeable and serviceable same as a portable spa Poly Internal Std Pulsator Deluxe, White Manf. Waterway Plastics Manf. # 210-6070 Poly internal Std Pulsator Dlx, Black Manf. Waterway Plastics Manf. # 210-6071 Poly Internal Std Pulsator Dlx, Gray Manf. Waterway Plastics Manf. # 210-6077 Waterway Poly Jet series. All Poly jet internals are interchangeable, so you can "mix and match" them. This jet has two rotating water outlets that spin back and forth creating a pulsating massage. This jet has a comfort adjustment, when you rotate the front face of the jet you can adjust the amount of water let into the jet. This jet internal comes with a 5/16" orifice installed and has a recommended flow rate of 9-12 gallons per minute.