Insulating Attic Door Stair Cover (Ayer)

Looking to stop your cold (and hot) air going out your roof? This Battic Door Attic Stair Cover fits folding attic stairs and is designed for 22′′ x 54′′ to 22-1/2′′ x 54′′ rough openings (actual cover size is 21′′ wide x 52-1/2′′ long x 13-1/2′′ deep inside dimensions, 21-5/16′′ wide x 53-1/4′′ long x 13-5/8′′ tall outside dimensions)
This is an older model and does not come with the nicely sewn thermal cover shown on the their website but instead came with a thermal "bubble wrap" foil sheet that you sticks on. We never used it.
Full details of what these are and install instructions are at https://www.batticdoor.com/product/attic-stair-covers