There are various types of Borosilicate Baby Feeding Bottles Nipple that can be placed over the own to help baby latch. They are soft and flexible, so they wont bother your skin, and should stay in place during feedings thanks to a suction cup-like design. These covers are plastic lids that snap over nipples when bottles arent in use. They are a nice feature when traveling to prevent nipples from becoming dirty or to help contain nipple leakage. The offered Borosilicate Baby Feeding Bottles Nipple are very effective. They are easy to install and made using high quality silicon.