A friend alerted me to this product and asked my opinion and I must say I just don’t get it. The opener is designed to open crown caps, twists offs, and to reseal bottles. Any crown cap opener will pop off a twist off so those are basically the same function. What I don’t quite get is the usefulness of the sealing function. Typically when I open a bottle I finish it. That may take some time so I guess one could use this to hold carbonation while the bottle is being consumed, but typical crown capped bottles go from about 12 ounces to 22 ounces so even if your glass only holds 8 ounces you are only going to fill the glass three times. To me it’s an opener with another function I will never use. Perhaps you see it differently. The cost is $10 and you can get them from any number of outlets. If you know something about this opener I don’t, please clue me in.