This adjustable regulator works with disposable oxygen cylinders, which can be found at hardware stores. Using pure oxygen is by far the most effective way to oxygenate your wort. Most brewers notice improved yeast health and attenuation after they switch to pure oxygen. The outlet is a 3/16" barb.
An O2 regulator that has a control knob where you can adjust outlet pressure between 1/32 and 4 liters per minute.