Part number 210-3927 is an "Old Faithful" High-Flow Swim Jet Assembly manufactured by Waterway Plastics.
It is a powerful directional jet capable of handling up to 175 gallons per minute (GPM), typically found in swim spas or as a high-volume whirlpool jet in large hot tubs.
The following hot tub and swim spa manufacturers use or have used this specific jet or compatible models from the same Waterway line:
Cal Spas: Waterway is a major OEM supplier for Cal Spas, and this specific part is frequently referenced in their parts documentation.
Wind River Spas: This manufacturer explicitly states that they use Waterway jets across their entire hot tub lineup.
Hydropool: Uses the Old Faithful series in their swim spa models and lists this specific part number as a standard replacement item.
Marquis Spas: Known to utilize Waterway's high-flow jet assemblies, including the Old Faithful and Dyna-Flo lines.
Dimension One Spas: Integrated Waterway jets, including Old Faithful components, in various model years.
