SaferCCTV Woodworker 3/4 Inch Square Hole Drill Bits Mortising Chisel Set, Mortise Chisel & Bit Set for Construction Installation Renovation Decoration Industry - - Amazon.com
A square drill for round holes
Woodworking Bench Mortiser Square Hole Chisel Drilling Machine Location Tool Tenon Joint Mortising Attachment Chisel Bit Mortise Tenon Drill for Bench Drill Steel USA Stock - - Amazon.com
7pc Square Hole Mortise Chisel Drill Bit HSS Woodworking ...