This is everything you need for an aeration system, minus the pump or oxygen source. Most aquarium style air pump will work, or attach to an oxygen regulator to use with disposable tanks.
Comes with inline filter, stainless steel diffusion stone, and tubing.
About the inline filters: There are two sides to the filter - an "in" and an "out". The direction you use doesn't matter, however, you want to take note of which way you first push air through it and always keep it that way. There is an arrow on the edge of the filter housing that we use to keep the air flow going one direction when using it. The filter should never get wet, so don't try and sanitize it by dunking it in sanitizer. To store the filter, use a little tinfoil on the "In" of the filter and store in a zip-lock bag.