At 4mo+, start with this 2-in-1 Bottle To Sippy Learning Cup, which is fitted with an interchangeable bottle nipple to silicone spout to help ease babies transition from breast to cup in their first drinking endeavors.The entire range is 100% watertight and leak-proof, open or closed or upside down. Use them at home or on the go – the range has been specifically designed with spill and temperature control in mind. Learning cup nipples are interchangeable, all spouts and straws made from 100% supple silicone, and the handles, which can help baby hold the bottle, can be removed if needed. As always materials are BPA, Lead & Phthalate free.