Valve On/Off, Waterway, 1" Slip x 1" Slip, Single Port, Gray

The part number 600-4367 is a generic plumbing component manufactured by Waterway Plastics, a major third-party supplier to the spa industry. It is described as a 1-inch, single-port, on/off shut-off valve, commonly used to control water flow to features like neck jets or waterfalls. 

Because Waterway sells this universal part to many different manufacturers, it appears in a wide array of spa brands. Identifying a definitive, complete list is difficult because spa makers often change suppliers or use this specific valve only for certain accessory lines.

However, based on common usage and documentation, here are manufacturers known to have installed this or similar Waterway valves in their spas: