As soon as I saw these I was super happy and ordered to right away. I really like the look of them however the cork bottom was glued so I had a very difficult time. I thought I could put it in my mug press upside down so the cork would stick out and not get heat but it's too thick . Apparently you cannot put cork in a convection oven but I did see a video on YouTube of somebody doing it with a silicone wrap so I went ahead and it was fine. Just a little difficult with your image and the cork bottom so you have to make sure you've got kind of a white background and not a full colored wrap or I think there would definitely be some ghosting on it. The other thing was I tested it out and it did not keep it much hotter than just a regular cup. I kind of thought it was going to keep warm for hours like the tumbler. Also not 15 oz. It is about 12.5 ,But they are still super cute and one of the teachers at my son's school ordered one for herself and two other ladies and they were very happy with them so I'm happy that they're happy. I was told they were going to order some more that had the removable cork so I will try it out again , even though it doesn't stay hot I do like the look of them.