Each crystal liquor tumbler is sculpted with a circular channel to match the exact proportions of the ice ball made by its accompanying silicone ice mold. Drop the icy sphere into the channel to chill your liquor faster and last longer than coarse cubes. Each set includes two crystal tumblers and two silicone ice molds. Instructions: Fill the hollow silicone ball with water and place in the freezer for at least 4 hours. Using the thumb grip; remove the cap to easily access the spherical ice ball inside. Place the ice sphere in your glass of whiskey, scotch, bourbon or any other liquor of your choice. The slow-melting ice ball will naturally roll in a circular motion on the base of your glass as you sip, cooling the liquor evenly.