CO2, or Carbon Dioxide, is the cheapest air source one can use to power their paintball gun. CO2 tanks come in a variety of sizes and most CO2 tanks can be refilled at any local paintball field or store. CO2 itself is temperature sensitive so using it in cold temperatures may cause a few issues. These tanks are available in 4 oz, 9 oz, 12 oz, 16 oz, 20 oz, and even 24 oz. The more ounces the more shots per fill you can expect to get! For commonly asked questions please look below!