The Tovolo King Cube Clear Ice System makes four crystal-clear 2-inch cubes at home. Foam insulation slows the freeze and directs it from the top down, pushing oxygen and impurities toward the bottom tray and away from the forming ice. The result is transparent cubes without cloudy spots or trapped bubbles. To use it, fill the center tube with filtered water and let it flow into the four silicone cube molds. Freeze for 12 to 16 hours, then release the cubes from the flexible molds. The large cubes melt very slowly, so whiskey, bourbon, scotch and craft cocktails stay cold without watering down quickly. The insulated system also seals out freezer odors for clean-tasting ice. The silicone molds are dishwasher safe. Wash the foam insulation and tray by hand in warm, soapy water.