The Robert Sorby sash mortice chisels have a trapezoidal profile to the blade, this shape prevents them from binding in the cut. A trapezoidal chisel has a wider bottom blade with than the width of the spine. The angle for this chisel is 2¡. These are a heavy-duty chisel and are designed to stand up to levering out waste from door locks, tenons and hinges. They are fitted with a traditional boxwood handle