Pinch to tuck the nipple away when you're on the go. Nipple locks firmly in the extended position (this is not designed to pop when it drops). The firm lock feature is recommended for babies that have developed motor skills—but can be used for younger babies, too. Won’t pop out of babe’s mouth. 100% silicone. No lead, PVC, BPA, latex or phthalates. Firm nipple safe for teething babies.