Air injectors are generally flat and fairly small. Some of them resemble "pepper pots" some have a cap where the air bubbles blow out from the sides. Others simply have a single hole. What they all have in common is that they are connected with air pipes to the air blower, via manifolds that distribute air to the individual air jets.
Grommet gasket for Waterway low-pro air injectors such as 670-2210
1" Spigot or 3/4" Socket. Adaptor style. Stainless steel.
Replacement cap only. White plastic.