The TASTER®, handmade and mouth blown, has two indents; at the bottom and on the side. These have a dual role: they allow one to hold the glass between two fingers without warming the content, and to aerate the wine, who's molecules will open up when swirled against them.
Hold the glass between two fingers. Stir your glass to aerate. You will notice the Smell the nose down the drinking you have heavy aromas (alcohol). Nose at the top of the drinking you perceive the entire range of perfumes.