I used above an equivalent system of "House Wine" I bought it several years ago. He showed leaks that were matter could not do it "empty" or air ended up going back into the bottle. This system of at VacuVin is much more efficient: + Shape of "caps" that it adapts to all necks + System "click" when the vacuum is used to pump just enough. + Caps are removable in part to clean (you can even skip some parts in the dishwasher) I pushed the test one step further by setting a bottle closed with this system: no leaks! A good investment if you want to keep the wine longer under better conditions.