Yep! We've purchased them our last two cruises. I think they were around $15 (sorry can't remember exactly). Its a 20oz mug. You take it to any bar or restaurant and get a 20oz refill for the regular 16oz price.
Someone on the boards once calculated how many you had to buy to break even (I am thinking 10). It didn't matter to us, since we knew we'd buy enough! Plus you have a great mug to take home with you.
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