On The Rock: The bottom of the glass has a 'rock' which creates a natural liquid motion increasing the nosing of aromas. Ice Ball: Fill the included silicone mould to the fill line & put in the freezer to make a single solid ice ball that outlasts traditional ice cubes. Rolling Glass: The shape of the glass makes rolling easy without spilling. A slight hand movement rolls the ice ball around the 'rock' evenly & cools your favourite scotch, whiskey or liquor to perfection!