Review on COKTIK 12oz Wine Tumbler: Vacuum Insulated Glass Mug with Lid & 🍷 Straw – Perfect for Coffee, Wine, Cocktails, Ice Cream – Glitter Purple, 1 PACK by Kimberly Saunders

Received a set for Christmas. Quite happy with them. They fit under my 4.5" tall espresso faucet. The listing doesn't mention anything that is dishwasher safe, so I tried it in the washing machine. Some water got into the air space of the thermal cavity. I was able to I could hear it shaking the mug by my ear. If you look closely you can see some seams that allow water to get in. I didn't call them about this as they didn't say it was dishwasher safe. The next step was thermal testing .I compared a thermal mug to a ceramic mug to stay warm longer.I set both mugs to the same temperature.I timed 25 minutes (enough time for a cup of coffee in my spare time) to see how hot one Metal cup becomes. Then I measured the cooling of the ceramic cup to the same temperature. The ceramic cup cooled to the temperature of a metal cup in ten minutes! means I had 25 minutes with the metal cup while I only had 10 minutes with the ceramic cup. As of 07/08/21 one of the cups had cracked or cracked (not sure). Water got in while cleaning and then dripped onto the shirt while using...the other 5 cups seem fine