Enjoy an ice-cold martini even on a hot day with these glasses. The martini glasses are double-walled glass with a unique gel inside. Put glasses in the freezer for at least 2 hours. Once frozen, the gel will keep drinks at a reviving 43°-53° F. And while the drink is cold, 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.