INSULATED WALLS FILLED WITH PROPRIETARY COOLING GEL work as a beer chiller when frozen. Pop in the freezer upside down for two hours to keep your beverage chilled between forty-three and fifty-three degrees Fahrenheit. Keep your beverages ice cold with this frosty gel mug. Works well with beer, soda, tea or milkshakes. Great for all occasions. Lounging around the pool, watching sports, or relaxing on the porch or couch. These frosted cups are made of high quality Polystyrene, for added clarity and strength. A BPA Free Product. Hand wash