Faber cylinders made in Italy are the standard for dive tanks.
Steel offers significant advantages over aluminum cylinders due to steel's much greater strength. This allows for thinner walls and smaller overall size for the same internal volume. Steel cylinders also have better buoyancy characteristics as aluminum tanks become positively buoyant as they empty and you must wear extra lead to counteract this whereas steel cylinders remain negatively buoyant throughout your dive.
This package includes a 12.2L cylinder, boot and Sherwood Pro Valve. The Pro Valve easily switches from yoke to DIN simply by removing a threaded insert.