Normally I wouldn't write a review, but since I keep getting "reminders" to do so, I will. I feel duped my this company. The product is worthless. The bottles I drink out of are roughly the same as a beer bottle, no bigger around but slightly shorter, and it just jiggles around. When used as a tumbler it doesn't keep drinks warm or cold any longer than a regular cup. And if you want a return, good luck. The links to set it up don't work and there is zero response to any messages to customer service. Definitely the worst purchase I made this holiday season and won't be gifting it to anyone.