SET 4, Double Wall Frosty Freezer Cold Mugs - 16OZ. RED These set of 4 piece Ice Cold Mugs are shatter-resistant and have special double walls filled with a fast freezing, non-toxic liquid They can be frozen again and again. Put them in the freezer for 2 to 4 hours, remove and pour your favorite beverage. It will stay ice cold for hours without being watered down with ice cubes. Comes with 4 pieces as one set. On sale now through Sept 30.