I was slightly skeptical of these, but now that I've used them, I'm never going to be without them!
Being a 'curvy' girl, I was constantly self-conscience of the 'headlight' issue, especially in my professional work environment where they keep the office space nice and cold. When I received these, I was sure they would be visible under clothing, as they felt thicker and stiffer than I expected. However, they are totally and completely invisible even under the thinnest and lightest color tops and that is while wearing an unlined lace bra and become much less stiff after they warm up during wear. They are very comfortable and I always forget I'm even wearing them. They are slightly sticky on the back which assures they don't slip out of position during wear. The product suggests that they can be worn bra-less as well, but I feel that would probably depend on the outfit since they are not as sticky on the edges as in the center so may not lay right if they didn't have something structured around them. Easy to wash and reuse. I would recommend this larger (8 cm) size if you're a larger cup size as they really do fit much better than smaller size petals.
Bottom line, great product at a great price point!