Bests & Worsts Reviews from Amazon

I bought mine a year and a half ago and have used them frequently. On the positive side, great glass bottles! Nice thick glass that will withstand most falls, especially with the tight-fitting sleeve on. Size is perfect for slipping into the water bottle holders on the outside of my backpack. The cheap tops are another story. They dent easily and the leakproof silicone ring is anchored by a small inverted cup-shaped piece of metal that is pressed onto the interior of the top. Over time this piece loosens and starts to slip, making it increasingly harder to unscrew the top without the silicone ring also slipping so that you have to grip the underside of the ring as well as the top to get it off. I countered this by gently screwing the top on so that there were no leaks but still able to unscrew it without too much trouble. Eventually the top came to pieces and I found the tiny metal cup sunk to the bottom of the bottle. Freaked me out a little because I wondered what the heck was floating in my milk as I drank. The silicone ring is nowhere to be found - hoping I didn't swallow it :) - and so the top is now useless. I am going to contact the seller and see if they will replace the top for me. I will follow up on that here once I get an answer. Mazel Tov! UPDATE: Company responded immediately to my phone call. Sent me six tops no charge within a week. With that kind of customer care I will definitely order from them again.