Tank

Alright your tank contains either C02, or compressed air, depending on what you buy. More and more people are coming to compressed air nowadays because unlike C02 the pressure doesn't change in hot or cold temperatures. Although air tanks cost more than a C02 they give a more constant pressure on them, also a C02 tank cannot be used on an electric powered gun, as it will freeze the electronics, whereas air can be used in all types of guns. Price wise a C02 tank depending on size can range anywhere from $20 to $60, while compressed air can cost from $50 to $230 for the top Carbon Fiber air tanks.