Directional SS Wave Jet 500 Series. When looking at the front of the jet, you will see 2 Gray Spots known as spokes. Found in 2009 or Newer Vita Spa by Maax Spas. This jet measures 5 inches across the jet face. There are jets that will measure 2 inches, 3 inches, 4 inches and 5 inches. It is important to measure the jet that you want to replace.