Use the link in my first post. It will work for the new upload.
I need to redo the rings with plywood. I get too much shifting with the 4x4s; they are not square enough. I want to increase the pressure. I can now do +129 millibars. I think that is about 10000 lbs of pressure on the side walls. I would like to double it.
Check out Darren's setup. The O2 concentrator system is nice. They cost about $500 to $700. The bags go from $2,500 to $20,000. The Box costs me about $1,800 and the wife can share it with me. She loves the alertness when waking up. No groggy mornings.