Left it in my car all day in July heat and the water was still cold when I got back. The 25-hour claim seemed like marketing talk until I actually tested it.
William★★★★★
Took this to the gym and the water was still cold when I got home five hours later, which honestly surprised me. The wide mouth makes it easy to add ice cubes and actually get them in there.
Violet★★★★★
Filled it with ice water before a morning hike and there were still cubes rattling around the next afternoon, which honestly surprised me. The 25-hour cold claim holds up better than I expected.