Gym flask. Stainless steel. I thought it was impossible to brake but it got really deranged when I forgot it on the balcony during a very cold winter night. The bottom of it bulged like an eye ball. But I fixed it with a hammer, now as good as new again.

@ndreas I just recently replaced that exact bottle with that exact bottle. First one lived over a decade until I did the same, left it in the car over a winter night, full. Couldn’t be salvaged. Klean Kanteen make great stuff.