A sphere has the unique characteristics of allowing the most volume to be contained within the least surface area possible. Therefore, an ice ball provides a drink with the least ice-to-alcohol contact ratio possible drastically reducing the rate of dilution. By comparison, crushed ice has low volume and a high total surface area, which is why it melts so fast in your drink.
In select bars you will find bartenders carving a cube of ice into a sphere for customers. Lately, for increased efficiency, ice ball makers like the Cirrus Press have been invented. Cirrus Ice Ball Press is the first to be manufactured in the United States with an exacting attention to detail and superior functionality over more expensive units.
Aluminum has the highest thermal conductivity of any metal not named Gold, Copper, or Silver. As a comparison, stainless steel has about one-tenth the thermal conductivity as the aluminum alloy we use at three times the weight. This means a stainless steel unit would weigh about 46 pounds and take approx. 4 minutes to make an ice ball as opposed to the 2.75” Cirrus Press weighing 16 pounds and taking only 50-60 seconds.
As for the operation - you simply place a block of ice on the bottom half of the Cirrus Press, place the top half of the assembly on the guide-rails, and let the Cirrus Ice Ball Press go to work. A minute later you'll have a perfectly spherical ice ball to impress yourself, your friends, or your customers with.