Gear Review: Hydro Flask 24-ounce Narrow Mouth Stainless Steel

Keeps coffee hot for over 24 hours, and water cold for more than 48!

Staying warm and well-hydrated is key to being able to maintain focus on important things, like filling out gear evaluation forms! This rugged stainless steel bottle has kept my coffee hot for more than 24 hours, and my Nuun-spiked ice water cold for more than 48 (both tests occurred at around 80°F). That’s some serious insulating power, especially considering the screw-on lid was off for the cold-water test. (Two competitive products didn’t pass the 16-hour mark in the same conditions.)

What’s the secret? Hydro Flask has perfected the art of the vacuum seal—in this case, removing all of the air from between two sealed walls of stainless steel. (Science 101: Everything that has matter—including air—conducts heat. So if you remove all air from an enclosed space, you eliminate conductivity, creating best-case insulation.) The powder-coated exterior finish doesn’t get hot or cold to the touch or sweat (nice if you use it at your desk, like I do), and it’s competitively light compared to other thermoses. $30; 11.5 oz.;