The black tank is extra. The aluminum tank is about 60 gallons, the relay valve is on the tank then the hose goes to the starter. The "push to start" valve can also be seen. This was from an IH COE tractor with an 8V71 Detroit.
I could not fit that one big tank and make it look good, so I had some made. I am glad I did, and I already have all the air starter related stuff, and all my plumbing for it.