Waterway is a very common OEM supplier to hot tub manufacturers, who often integrate these parts into their own spa designs. Brands that are known to use Waterway jets in general, or have specifically used the 210-7310 (or equivalent) in their models, include:
Cal Spas: This specific part is sometimes referenced in Cal Spas parts lists.
Wind River Spas: This company explicitly states that it uses Waterway jets in every hot tub it makes.
