I suggest that when it is over 85F and humid most of us would empty this 40 oz bottle pretty quickly. So it does not matter too much how long it will keep something cold. Also keep in mind about condesation. This is a metal canteen that will sweat or condesate through the bottle to the outside when it is hot. You can fit usual size ice cubes through the mouth
The canteen looks and feels nice. I think the value is pretty good, but after several washes, my water still tastes like metal. I'm not very fond of that.
I love having it. The only thing was I thought that it would be somewhat insulated. I put ice and then fill with water and it sweats like crazy. It is really wet and I have to dry my hands after driinking. But the size is great. I drink a lot of water and this allows me to have some without constantly refilling and to top it off it is not plastic so with all they say about reusing plastic containers, this makes me feel better when I drink my water.
The canteen is good as a container if you do not plan to drink from it. It needs a sports top for ease of drinking and a cozy to help keep contents cool/hot longer.