Stay cool all day. Nobody needs a warm protein shake. With this double wall insulated steel shaker from Smartshake, you’ll keep your drink ice cold for up to 6 hours. Inside, you’ll find volume markings in both milliliters and ounces, and a curved bottom that prevents protein powder from sticking and makes cleanup that much easier. Not for use with hot liquids. Always open the snap cap with caution. Do not use in microwave or freezer. Hand wash only.