No. 4531: The "T" on this square is 1/4" thick with 1/2" guide edges, giving ample anchorage whether on the cutting table or the drawing board. Tee-square has 5" rules on both sides for vertical ruling. The blade on the square is 3/32" thick. Blade edges are divided in inches with 1/16" increments on one edge and 1/8" on the other. Blade is 2" wide and 72" ling. Made of hard aluminum.