Our steel cylinders are manufactured at Worthington Cylinder's state of the art facility in Tilbury, Canada. The cylinders are manufactured using the Deep Draw and Ironing (DDI) process. Cylinders start from a circular plate of chrome-moly steel. Multiple draws on a hydraulic press transform the plate into an open ended shell. The shell is then closed, the neck is formed and the threads are machined. The DDI process produces the most consistence wall thickness resulting in the lightest weight, most efficient cylinders. This manufacturing process is what allows us to supply cylinders with the best buoyancy characteristics for scuba diving . Other suppliers are selling cylinders that are manufactured using the Billet Piercing or "Spun" Tube process. These cylinders are generally heavier with less preferred buoyancy characteristics than those manufactured using DDI.