I got the vacuum bottle caps actually only bought because I wanted to avoid the Amazon Postage and instead buy something useful. The operating principle of "air suction of liquids" me was a mystery when ordering. Now, thanks to the rubber rings to fit the locks onto any standard wine bottle or oil. The plugging of the suction hose and the vacuum sealing process ran off without any problems. Only ... when reopening, there is no difference, no matter how small "plop" or "sizzling", nothing.
The obvious can not be developed because a lot of "vacuum". Whether that what good? Soon I will prefer to pay the postage.
Update
It has nevertheless used what. Preliminary vigorously pressed it, then it makes afterwards still slightly "plop" -D
