Chill them in the fridge or freezer and your wine will stay at the perfect drinking temperature until the last sip. A cooling gel sealed inside is precisely engineered to keep your wine at the optimum temp. For red, refrigerate for at least two hours; for white, freeze for at least two hours. Cups are BPA-free plastic with an insulated silicone band for comfortable handling. Each 4 ¾ " cup holds 8 oz. Hand wash. Set of 4 as shown.