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We love insulated stainless steel water bottles for a few reasons. They keep beer cold in the summer and coffee hot in the winter, they’re lighter and more durable than glass, and they’re free of the chemicals found in some plastics. But not all bottles are created equal. We put five of our favorite models through the wringer. Here’s how they stacked up.

The Water-Bottle Test

Thermoregulation: I filled each bottle with a 35-degree water-and-ice mixture. I left each bottle in a room heated to 70 degrees and measured the change in temperature after 24 hours. To test how well the bottles retained heat, I poured 190-degree water into each bottle and then let them sit for 12 hours in my 70-degree kitchen before taking the temperature again.

Durability: We kept things reasonable at the start: dropping filled bottles from a porch and workbench, setting them atop a car and driving off, even jettisoning them from a pack while scrambling over rocks. But these bottles withstood the everyday abuse, so we ramped up the punishment: We teed them off a 50-foot cliff with a driver and shot each bottle with birdshot at a gun range.

Sigg Thermo Classic 0.5L with Tea Filter ($30)

Heat: 139 degrees after 12 hours. Temperature loss of 51 degrees.

Cold: 36 degrees after 24 hours. Temperature gain of 1 degree.

Durability: The lid broke as soon as we dropped the Sigg Classic from the workbench, but the body withstood the abuse like a champ with only a few minor scrapes and dings. Even after getting rocketed off the 50-foot cliff, the water bottle could still hold water.

The Verdict: The thermoregulation on this bottle blew us away. Out of all those we tested, it kept its contents the coldest—the water only got one degree warmer after 24 hours. While we liked the stainless steel tea filter that’s integrated in the lid, we didn’t like how tough it was to unscrew.

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Klean Kanteen 20 oz Insulated ($30)

Heat: 111 degrees after 12 hours. Temperature loss of 79 degrees.

Cold: 38 degrees after 24 hours. Temperature gain of 3 degrees.

Durability: The Klean Kanteen won our durability contest. It aced all our real world tests, took the golf swing as well as any of the other bottles, and finished the session with a still-functional plastic lid.

The Verdict: The Klean Kanteen had by far the most durable lid, kept our cold beverages very cold, and was the easiest bottle to fill with ice cubes thanks to its wide (2.130 inch circumference) mouth. And to be fair, the company says the bottle is designed to keep drinks warm for six hours, not 12.

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Miir 500 ml Vaccuum Insulated ($30)

Heat: 114 degrees after 12 hours. Temperature loss of 76 degrees.

Cold: 45 degrees after 24 hours. Temperature gain of 10 degrees.

Durability: The Miir’s body suffered a devastating impact when we dropped it off the porch, though the lid did survive until we teed it off a cliff. But this bottle was the lightest we tested, even if it was the least durable.

The Verdict: We love how easy it is to take the ergonomic wedge lid off with a single finger. Miir also donates a portion of the proceeds from these vacuum-insulated water bottles to get clean-water access to people living without it.

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Avex 24 ounce Brazos Autoseal Stainless Water Bottle ($30)

Heat: 115 degrees after 12 hours. Temperature loss of 75 degrees.

Cold: 48 degrees after 24 hours. Temperature gain of 13 degrees.

Durability: The Brazos’ Autoseal lid has a handle and a push-to-open spout, and we were convinced both would break early in our test. We were wrong. The lid survived the session—and is still 100 percent functional. The body withstood the abuse, too, and could still hold water after getting shot at.

The Verdict: If you need a stainless steel insulated bottle that you plan to sip on throughout the day, the Brazos is your best bet. In my past experience, I’ve found it maintains temperature even if you open the spout frequently, something few other bottles can manage.

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Hydroflask Insulated 21 oz Water Bottle ($28)

Heat: 127 degrees after 12 hours. Temperature loss of 63 degrees.

Cold: 42 degrees in 24 hours. Temperature gain of 7 degrees.

Durability: This bottle’s body proved to be incredibly resilient. It took the most direct shot from our gun and still held water at the end of the test.

The Verdict: We’ve written about Hydroflasks before and have been happy with both their thermoregulation and durability during real-world use. We also like the look of the powder-coated matte finish.

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