Duck House NCAA Unisex Crystal Freezer Mugs Place in freezer one hour or more prior to use, when frozen crystals will turn a frosty white color 16-Ounce mug combines state of the art refreezability with team colors and graphics Filled with non toxic, refreezable crystals Eliminates the need for ice as the technology keeps drinks "crushed ice" cold for hours without the watered down affect of ice Not recommended for Dishwasher or Microwave