These birch plywood blanks are ideal for pyrography, scroll sawing and laser cutting. Each blank is A4 size (210mm x 300mm) and 4mm thick. Cut from sheets of laser safe (low fume) Birch ply sourced from an environmentally friendly renewable source. Please note: Wood is a natural product and the layered construction of plywood can cause stresses that can cause mild warp and bending, High levels of moisture can make the bend and twist more pronounced. Storing in a warm environment with a heavy weight or heavy board on top will minimise warping but some warp and bend is to be expected. This is a BB grade ply which means some sides on some sheets may have plugs where knots have been removed but this does not affect the integrity of the ply.