I prefer the 2x 4 sheets...got a 4x4 sheet once at a good price but was shipped tightly rolled...and sat in Texas sun for 1 105F day took a set
The curl was only one problem...While I have a large 16 x 24 shop, finding a way to open the 4x4, lay it flat with weights to cut what I needed, was a royal PITA
I believe I get most of mine now from Tom Morris....but 4"x 36" only ----ships flat ----and a size that suits me