The Thinkbaby feeding system is a transformational line of products that is meant to follow your child from newborn to toddler and up. This conversion kit turns our Thinkbaby baby bottle into our award-winning Sippy! The convenient handles are made of polypropylene, and encourage motor skill development in your little ones. The spouts are extra-soft, medical grade silicone. Reduces environmental waste by adapting to your child's growth, rather than requiring an all-new bottle when they outgrow bottle feeding. Dishwasher safe, top rack recommended.