1/4" Marine grade unfinished plywood in either Fir, Meranti, or Baltic Birch. This plywood is good on one side with an A grade front that is smooth sanded and clear face. The back side is a B or C grade that is also smooth sanded and knot-free but does allow for a blemish. Marine grade plywood has solid plys with no voids and a pholic exterior glue. This plywood is not treated. Our plywoods are sold in larger sheets at the lumber yard and cut down to smaller sizes. Please allow 1/8"+/- variance in size to allow for saw blade cutting.