#1 - These are NOT 3x6ft as others have stated. They are exactly 34" X 68"
#2 - There are NO pre-drilled holes for mounting. However there are equidistant injection molding circles (see pic) across all four sides that measure accurately so you can drill your own. 
Quality out of the box looks good. Bought six, packed 3 per box. These appear to be molded polyethylene plastic. Thickness is 1/4" so they should weather OK but they're flimsy, not rigid. Will need mounting or a support frame. I'm using 4" standoff mounts against the wall to mount them as decorative panels, which will be tricky to measure accurately but provide good support.