Air Injector on Left Hand side - Used by Monarch Spas 10+ years ago - NO LONGER AVAILABLE Original hole size - 5/8" / 16mm - has a salt shaker cap and large black o-ring seal - the caps are prone to snapping off, exposing the o-ring from inside the spa. The body is fairly bulky, square in shape with deep ribs, 3/8" / 9mm RB hose connection at rear - in-line. The only air injector available for direct replacement is the Waterway Multi-Body air injector shown on the right hand side - it requires a hole size of 9/16" / 14.5mm. Therefore it fits with a little extra space, but plenty of sealing surface. The 3 barb options on the rear make it a universal replacement. See this air injector above - ww670-2607 - select white.
