Oh, I bought their 'water heater insulation kit'
It worked out perfectly- 48" wide, so I had to cut down the middle to size, but the length was perfect - about 75" - for a SHC Sprinter. And 2" think. I used aluminum duct insulation tape to tape everything to the ribs- but I first used spray glue on the batt and the ceiling, to stick it up. Then, 1/4" Luan plywood as ceiling. The unfaced R13 3" thick batts were too thick for the ceiling, but perfect for the sidewalls.
The stuff does make a fair amount of dust, but no itchy-scratchy like fiberglass.
I recommend the denim.
Very quiet, much better than rigid pink squeaky foam