The kit contains 0 ml of free-flowing urea. The CLOSER to Nature® series of Tommee Tippee bottles helps to combine breastfeeding and bottle feeding. The nipple is designed to mimic the natural softness, touch, and movement of a mother's breast. The bottles are easy to care for: they can be sterilized, frozen, and heated in the microwave. 260 ml bottles with 0% Bisphenol A content.