Glass on the inside with a protective plastic outter layer, so the milk never touches the plastic! 🍼👶🏻 mom of 2, baby items, baby bottle, expecting moms, pregnancy, boy mom secondtimemom babybottle babybottles babyitems babymusthaves babyregistry ltkbaby momof2 expectingmoms glassbottle LTKKids LTKFamily LTKBaby