My partner and I bought these for Christmas as part of a pledge to take home-brewed coffee to work instead of funding the college educations of the children of coffee shop big-wigs. After I figured out the unnecessarily complex lid, they worked fine. Until one ding on the bottom compromised the insulating capacity.Now, I've had to call and order two new lids (it's 9 months later), which they were happy to send. First the locking mechanism got loose and would unclench as I opened the lid for drinking. I lived with that. But now large cracks have appeared in the threads, making them a leaky mess.I went back to my thermos-brand bullet bottle, which even after dishwashing and dinging and years of use keeps a vacuum seal and keeps liquids hot for 24 hours.I paid $15 for the thermos and $30 each for the Stanley mugs.