The 5 Lb. Aluminum CO2 Tank is a great size that fits in almost every refrigerator, plus it is still small enough to take on the road. This tank will usually carbonate and dispense 10 or 12- 5 gallon kegs per fill up. Note: Federal law requires that the CO2 tanks be shipped empty. They can be filled at your local welding supply shop, or look in the phone book under Gas-Industrial, Medical. Proposition 65 Warning for California Consumers: This product contains chemicals known to the State of California to cause cancer and/or birth defects or other reproductive harm.