Bottle & interchangeable system. Easier to hold for you and your baby. 1 silicone nipple included. Mixing disk included. A choice of nipples. A wider opening than most other reusable bottles. Easier to fill without spilling. Easier to clean. Mixing Disk: Designed for mixing powdered formula. Wider Bottle Opening: Easier to fill without spills. Easier to clean. Contoured Shape: Easier to hold for you and your baby. Wider Base: More stable during use and storage. Wider Nipple: Three natural nipple shapes designed to feel more like mom - so baby can choose. 3 new traditions nipple styles. Let your baby choose. It often takes two or three tries for moms to find a nipple that baby likes. Now it's easier than ever to find just the right one. All three nipple styles fit the New Tradition Dual Purpose and Contoured nursers. Soft texture and natural shape designed to feel more like mom. Made of silicone. Three flow rates for each style - slow, medium and fast. Your baby can pick one that feels the most comfortable and familiar.