ProX's UltronX series cases are made from Polypropylene Copolymer, making these cases crush resistant, and virtually indestructible. This rugged case features a sealed ring, which makes it airtight and watertight. The automatic air pressure release valve will equalize the air pressure, which allows this case to be airline friendly. ATA/TSA approved and ideal for air travel. An excellent way to keep your microphones safe, dry, and out of harm's way when you travel either locally or long distances.