I tried just about every brand a few years ago on a west wall I
rebuilt, the blue board won as somewhat effective, the foil covered
white crap is landfill. Only the blue board is only slightly more
effective than an empty space even when fitted with surgical precision.
A poorly fitted R-13 fiberglass did much better. I've ripped most of it
out and replaced it with R-16 fiberglass. The blue has its uses, and I
would use it again, it has the advantage of being softer and tighter so
accurate cuts can be made with out the shattering and crumbling the
white stuff does. Any place the bats will fit, isn't one of its uses.