This chisel is designed specifically for squaring off the corners of routed hinge gains. The 9.5mm(3/8") square blade is precision ground with a 35° bevel on each face, made of long wearing A2 tool steel, and hardened to Rc60. Though it can be used on its own, greater accuracy is ensured by use of the 50mm tall anodized aluminum guide block. Two embedded rare earth magnets hold the chisel squarely in place, while the outside faces of the block register against the routed pocket. A tap on the chisel cuts the corner square and flush with the routed edges. You will come to appreciate the fine edge and long wearing properties of the chisel when you finally have to resharpen it, as sharpening corner chisels is never an easy task!