This brand new, 20 lb aluminum CO2 tank ships free in the 48 contigous states, and because it is made of aluminum rather than steel you can feel confident that it will never rust. It’s called a 20 lb tank because it holds 20 lb of compressed (liquified) CO2.
All new CO2 tanks are shipped empty and will require either filling or exchanging for a full tank. Most local homebrew shops will stock gas to exchange, and many local welding supply companies can fill tanks on site.
CO2 tanks should always be stored in an upright position.