Formed from injection molded composites, the Composite Sanding Block, No. AF4415, from Dura-Block has been optimized to work with flat surfaces. Utilizing a patented hollow design, the block is distinctly rigid while weighing less than a third of an ounce. The blocks are compatible with standard rolls or pre-cut 2-3/4" self-adhesive paper. The blocks come 1-1/2" high by 2-5/8" wide by 11" long.