They actually help prevent our beautiful walnut liqueur with ice cubes, but they are not as effective in terms of conservation freshness over time. It cools a little liquid, but it must provide at least 3 per drink to feel a light refreshment. Otherwise they are very engaged, just rinse them and I put them in a freezer bag in the freezer, ready for next use. These are certainly not the best quality that we can find for sale, I have unfortunately no point of comparison, but they are not very expensive compared to some. Perhaps well-washed pebbles would do the trick? .... However I use every tasting.