The Aspirator Valve allows you to use co2 on a cask at very low levels: perfect for a cask of ale that you want to have around for more than a couple days, but don't want to get overly carbonated. The Valve will vent small amounts of excess co2 from secondary fermentation or temperature changes, but will also provide a consistent blanket of co2 when pulling off pints. The Valve is nonadjustable and provides a level of co2 just above atmospheric pressure. It should not be used for venting a new cask. Needs to be mounted in correct orientation using the included eyelet mounting holes and screws. Use with 5/16" Beverage Tubing and a clamp on the inlet side.