The bottom of the Rolling Rock Whiskey Glass has a “Rock” which creates a natural liquid motion, increasing the nosing of aromas. Fill the included silicone mold to the fill line and put into the freezer to make a single solid ice ball that outlasts traditional ice cubes. The shape of the glass makes rolling easy without spilling. A slight hand movement rolls the ice ball around the ROCK evenly and cools your favorite scotch, whiskey or liquor to perfection. Holds up to 8oz.