Klean Kanteen® bottles are made of heavy gauge stainless steel and outperform all other metal bottles in independent tests. But they can dent if you drop them. Our one-year warranty covers manufacturer’s defects only, not damage caused by using our dropping your bottle. If you dropped your bottle and dented it, odds are the dent is inward. In some cases you can put a wooden dowel or a wooden kitchen spoon inside the bottle and tap on the other end with a hammer to push the dent out. DO NOT use a metal object to bang the dent outward as the metal can get inside your Kanteen®. You can also further damage or even puncture your bottle. Even if you’ve dented your bottle, it’s still totally safe and free of harmful substances. Because every Klean Kanteen® made if 18/8 food-grade stainless steel through and through with no liner on the inside, a dent, no matter how large, will not change the composition of the metal.