It plugs the escaping gas that causes it to go flat and prevents spills. So far I had 0 issues, hopefully it stays that way for a long time. Not a very good watch, first of all, yo cant answer phone calls, it lacks sound, and sleep tracking and exercise tracking apps are not accurate, this watch should cost 100$ max and it would be expensive, as an Apple Watch owner as well this watch only looks good to see the time the rest Samsung should not sale this item anymore is very limited. Theyre sturdy, they fit on my small walls, they hold up well and came with many extra hooks. Excellent sound quality for the price, Ive been looking at a lot of comparable speakers and I do think this one has the better bass. Now that they are made in China, I say, DO NOT BOTHER! Programability: TBA. This receiver isnt in that best-of-best stratified league but its hard to dispute that it is exceptionally high on overall value, functionality and usability and for those factors it earns 4+. I would have had the sound turn up properly using the hardware volume button. See separate review.