Leaves your water fresh for days. Stands up to a beating along the trail. Will last for years as long as you keep it away from fire. For some reason, a lot of my friends think that when their water freezes, they should put it next to the fire to warm it up, this usually results in one of them blistering their Nalgene and working themselves up over it. These bottles will help keep your water from freezing a little, but you should keep it at the bottom of your sleeping bag to prevent them from freezing in the first place. If they do freeze, use your jet boil or however you want to get hot water and poor some into your frozen Nalgene. This will free up your frozen hydro-resevoir and prevent you from ruining your bottle. You can then pour the water back into your boiler and re-heat it and repeat until your Nalgene is ice free. Also, these won't hold the taste of flavors, so feel free to add some Propel or Gatorade to your bottle. Lastly, these are super durable, I have seen them fall pretty far and come away with just some scrapes. They aren't invincible, but I haven't found anything more reliable. I still prefer them over a camel back for extended back packing with heavy loads. No issues with leaks, these guys are reliable.