I bought this mug because I'm on the go a lot. The day after I received it, I had a doctor's appointment and didn't have time to drink my tea. So I put it in my new "spill proof" thermos mug to keep it hot while I drove. When I stopped for a traffic light, I picked it up to drink it, and it spilled hot tea out all over my clean shirt and down into the crotch of my pants. The burning and embarrassment!!! When I got home, I cleaned it and started filling it and testing it. I tried this a bout 15 times, and every time it leaked. I would tighten the lid, but there was always a tiny slit where it wouldn't close tightly even though I firmly screwed it on. PIECE OF CRAP!!!!!!!