The Beer Cork is a high-quality closure made of natural cork, specifically designed to fit Belgian-style beer bottles and to preserve beer flavor and carbonation. This 'micro-agglomerated' cork is composed of small, uniformly-sized cork granules. Before the granules are molded into their final shape, they are cleaned with supercritical CO2 to remove harmful chemicals that can affect flavor. Because the corks are designed for a tight fit, a Champagne corker is required to insert the beer corks. After insertion, the straight cork will take on the classic 'mushroom' appearance. A cap and wire hood are required to ensure that pressure from the carbonated beer does not force the cork out of the bottle. Length: 44 mm Diameter: 25.5 mm.