For the ultimate folding attic stair insulator, go to attictent.com. The Attic Tent mounts permanently in minutes with zipper access. Not only does it prevent air in/exfiltration, it also stops fiberglass & dust particles entering the home, thus improving indoor air quality. It is the only attic stair insulating cover on the market that I know of, that meets the national home building code. ASTM-E84-03 Tested, FR treated, blower door tested, engineers calculated savings and energy efficiency. Go to www.attictent.com and view the videos of the Attic Tent in action.