I have been using the silicone nipple covers for several months. Wash per instructions and air dry.  They are very comfortable.  I have been amazed the way they are reusable and still able to stay on your body.  I live in the south, where heat temperatures are high.  Sweat doesn't seem to affect the staying power of the nipple covers. I am a size  D, and have worn under a thin bra. My breast are still firm so I have also worn without a bra in this sweltering heat.  No one is the wiser. Have purchased, two more sets, one for me and one for my daughter in law.