The Decodyne 18 oz. acrylic freezer mugs are crafted with a fun "crystal-frosty" appearance, which actually consist of non-toxic freezer gel, sealed into the side walls of your mug. That is where the secret of freezer mugs lie. By placing these handy acrylic mugs into your freezer for about two hours (they work best when placed upside-down) the freezer gel freezes, offering you a unique way to keep your beverage icy cold. Although they are hand wash only, these mugs are durable and convenient for any busy bar, restaurant or lounge. To add an extra flair to these already stylish designs, you can choose these freezer mugs in either Blue, Clear or Red.