Plastic.Offers a long lasting chill to keep your drinks cold for longer.Fits perfectly into Premium Cooler Bags and Cooler Tote Bags.FDA approved.Low profile design makes it space friendly in both your freezer and Cooler Bag.Fits perfectly into Premium Cooler Bags and Cooler Tote Bags.Measures approx 8"W x 12" L x 1.5" D