CO2 is a liquid and takes time to expand into a gas. The gas is what we use in paintball to propel the paintball down the barrel and "fire." Liquid CO2 expands to gas very rapidly, and if any gets into your paintball gun it can effect your velocity fluctuations as much as 20-30 feet per second. This greatly effects your consistency on the range and the accurqcy up and down. Using an expansion chamber will help alleviate this issue greatly. These specially designed chambers keep the liquid CO2 out of your paintball gun and give an area for the liquid to expand to a gas. This will greatly increase your consistency. This will also give you a few more shots out of your tank and increase your accuracy.