Labor Saving And AccurateThis Professional Mortising Chisel Ideal For Drilling Square Holes In Wood With Mortiser Or Mortising Attachment. And Reduce The Labor Intensity Of Construction Workers, Speed Up Construction Speed, Reduce Construction Costs For Construction, Installation.How To Do The WorkThe Square Drill Into The Drilled Hole By The Rotating Body, While The Impact Of The Use Of Percussion Force Transmitted To The Outer Body, The Round And Square Hole Crushing Material Head Wall, And The Debris Will Be Discharged From The Tube At The Same. 6 Different SizesComes With 6 Different Size: 1/4Inch 5/16Inch 3/8Inch 1/2Inch 9/16Inch 5/8Inch, Suitable For Opening Different Square Holes.MaterialSteel, Heat Treatment, High Hardness, Sharp Blade, Continuous, Cuttings Fast, High Efficiency.ApplicationFits All Mortising Machines And Drill Attachments. Square Hole Drilling Is Mainly Used For Woodworking Aspects. Please Note: The Chisel Alone Does Not Work In A Wood Drill, You Need An Attachment For Your Drill.