The cool new Roller Rock Glass Setincludes a unique shaped whiskey glass that lets ice spheres made from the included ice mold roll around the bottom of the glass, properly chilling your drink without diluting the flavor. Ice spheres are the preferred way to enjoy drinks on the rocks, because they have a smaller surface area than traditional ice cubes, so the ice melt slower, preventing the drink from becoming too diluted. A great solution and gift for whiskey and Scotch on the rocks drinking connoisseurs.