These are older Larsen & Luxfer carbon dioxide cylinders 12 are 50 Lbs ones (3 are full) and 10 are smaller 20 Lbs ones (2 are full). Note: Some of these have older date stamps (including 1997 stamps on the smaller ones) and will likely need professional recertification/hydro-testing before a local gas supplier fills them. Many places will take them as trade-ins/exchanges. Cash or Venmo only. Will sell them separately, send me a message.