This is the proven pre-built ready-to-bury completed Mini Blast & Fallout Shelter. This shelter was originally designed by the Oregon Institute of Science and Medicine. utilizing 14 gauge galvanized corrugated steel (under road use type) for 50 psi blast and well in excess of 1000 PF fallout protection. Double entry/exit risers with double welded (inside & outside) 10 gauge steel plate bulkheads and 1/4" steel blast doors. With this pre-built, pickup truck delivered, shelter and less than two hours of backhoe work later, it's in-place in (beneath) your backyard.