Pigeon Breastfeeding Real Feeling Nipple for Baby Bottle Size: SS Purchased at different times. These have been used for several months, so there may be some yellowing. Please understand that these are used items. They have been washed, sterilized, and stored together in a Ziploc bag, but please sterilize them again before use. When mailing, I plan to fold the nipples. Set of 4 silicone round nipples for baby bottles. - Quantity: 4 - Material: Silicone - Shape: Round - Application: For baby bottles Thank you for looking.