Use to create straight edges, square off material and produce perfect dihedral angles. Block sand large areas, profile wing leading and trailing edges, etc. Made from anodized aluminum extrusion that is light and easy to handle and will not warp. Tungsten carbide sheets are bonded to the extrusion with industrial grade double-sided tape. The Flat blocks will sand a perfect 90 degree angle when placed on their edge. The Wedge block allows you to sand into tight corners and the Contour block enables you to sand convex or concave areas.