Large bottles holds 27 ounces Medium bottles hold 17 ounces The Retap bottles are of the highest quality! That is why we prefer borosilicate glass. Safe, strong and reusable. An our Danish design has been rewarded with a Red Dot Design Award in 2011 and the Good Design Award in 2012 Borosilicate glass will not wear down over time, but calcium and magnesium in tap water can leave (unharmful!) off-white marks on the glass. If your dishwasher is not able to remove these marks, we have a few tips to make your Retap Bottle shine like never before. Retap tops are very unique as well. They do not leak! Stick them in your handbag, backpack or briefcase and do not worry that you will find a pool of water at the bottom like so many of the tops of other bottles. Retap tops are made of thermoplatic elastomers (TPE) which are completely safe. Further, when you actually drink the contents, you only ever touch glass. Our tops fit nice an snug. They will not accidentally 'pop off' and you can take them off easily especially when there is a little liquid in the bottles.