Save yourself the clutter and the cost by putting that cupboard full of mason jars to good use! The Mason Bottle DIY Kit includes everything you need to convert mason jars you already have at home into easy to clean, cost effective glass baby bottles. *The DIY Kit does NOT include a jar* Mason jars are freezer safe so you can easily store breast milk in the mason jars and then warm and serve from the same jar -AND- you can use the jars to store homemade baby food. Benefits: -Milk flows smoothly with no air bubbles and no leaking -Dual-valve ventilation system to prevent gas and colic -100% Made in the USA -Easy to Clean -Non-Toxic, BPA and BPS free -Approximate volume markings on sleeve