These pieces are part of the Watkins Moto-Massage DX jet system, which can be found on some Hot Spring spas.
The silicone air tube is included.
Note: The Moto-Massage Jet and the silicone air tube will stretch over years of operation. If your existing air tube has stretched then your existing Moto-Massage has also stretched. The entire jet assembly will need to be replaced.
Maximum diameter : 57 mm
Maximum length : 335 mm
Air tube length only: 230 mm
Watkins / Hot Spring part numbers
Moto jet : 77242
Air tube : 70307