Those that are truly serious players are turning to a paintball air compressor containing nitrogen or simply compressed air. While the use of nitrogen offsets some concerns that other propellants posses, it does not come without its own set of issues. However, its major advantage is that as it expands and cools it does not have to change from a liquid to a gas as carbon dioxide does. Because it is not required to change from a liquid to a gas, the variations in pressure (common with rapid firing) is also reduced allowing for increased accuracy. On the other hand, nitrogen must be stored at high pressure (34 MPa) while carbon dioxide only requires a storage pressure of 8 MPa. Many people need to buy air tanks, but they do not have sufficient amount of information regarding it.