I’ve tried many different brands and types of nipple covers / bra alternatives, and these are by far the best available option. That said, they are not actually invisible under most of my clothes.
What I like about them: the quality is great. I got a solid three months of frequent use out of my first pair, and even after three months they were still sticky! They are comfortable to wear and easy to apply. They stay on, even when I’m active — I’ve even worn them to yoga. They are painless to remove and don’t leave any residue on the skin. The carrying case is great, and makes it easy to keep them clean and sticky when not in use. They’re thick enough to keep my nipples from looking pointy.
What I don’t like: unfortunately, they’re not invisible. The outline is actually quite visible under most of my clothes. I live in a hot climate, so I wear a lot of light and thin fabrics. The edges of these nipple covers are thick, which makes the round outline quite visible if I wear anything light, thin, or form-fitting. I’ve included photos in both bright and dim lighting and in two different types of shirts so that you can see.
Overall these are still by far the best available option for a bra alternative. I just wish they were a little less visible under my clothes.