Enjoy a nice cold drink or smoothie without it getting warm. These tumblers are double-walled BPA-free plastic with a unique gel inside. Once frozen, the gel keeps drinks at refreshing 43°-53° F. And while the cups are chilly, your fingers won’t be. A silicone band makes the cups comfortable to hold. For best results, freeze glasses upside down for 2 hours or more. Hand wash only.