Aeration is beneficial for supplying yeast cells with oxygen for reproduction and fermentation. Aerate wort after it has been chilled and before yeast is pitched. Comes with pump, sanitary filter, tubing, and stainless steel 2 micron diffusion stone. This system never runs out of oxygen. Filters down to .023 micron at 99.99%. Both 1/4" and 3/8" tubing will attach tubing will fit snugly in standard stopper. Full instructions included!