I bought a lot of these for my plants when we were going away for a couple of weeks, and they did a great job of keeping my plants alive. I didn't have enough wine bottles for all my plants, but they also work with 1-liter seltzer bottles, and I used some glass soda bottles for my smaller plants. I have actually left them in since getting back from vacation, and my plants have never looked happier. My peace lilies, spider plants, and ferns, in particular, seem to enjoy the slow and steady watering. I just fill them once a week (or less often, depending on the plant) and they are good to go.
During my two weeks of business trip, I used five stakes for a larger planter with basils and shiso plants and one for a flower pot. the bottle for the flower pot was empty when I came home, however the bottles in the larger planter were still half full. It regulates the moisture level without over watering. It does what it says. Highly recommended