How a neoprene sleeve keeps water cold even in the hottest weather.

Until recently I was using bottles from the Swiss company Sigg. They really do last forever. However mine were starting to peel on the inside and were getting hard to clean even with tablets — Brno's hard water probably does its damage. So I started looking for something non-reactive and lightweight — glass! I ended up with drinkit. The practical neoprene sleeve insulates the bottle while the glass keeps it clean.

The real test was on holiday, where I carried it on my backpack. It was hot outside, over 30 degrees, yet the water stayed as fresh as when I'd poured it. Drops from moderate heights onto sand it handled without a problem. Getting sand out of the neoprene isn't an issue either. It exceeded my expectations. Now the cold weather is coming — I'm curious how the glass and neoprene will handle that.

It has one downside: the largest volume available is 0.7 l, which is personally not enough for me.