Sorby 331-5/16 Sash Mortise Chisel, 5/16 in. The heavy sectional profile makes the Robert Sorby Sash Mortise Chisel ideal for getting the leverage needed to remove waste for mortises, lock insets, and hinges. The trapezoidal shaped 5/16" blade has a 2 degree side relief angle to help reduce binding in use. Chisel has a 5-5/8" long blade and an overall length of approximately 11-1/4". Boxwood handle. England Model: F33108B