Manufactured from selected steel these boring bars are accurately machined. Bars incorporate broached holes that accept standard high speed steel or carbide toolbits conveniently. Bars are supplied with an allen-key but without toolbits. Boring Bar Length: 5-1/4 inch (133mm) Boring Bar Diameter: 7/16 inch (11.11mm) Holder Length: 2-1/2 inch (63mm) Square Size: 5/8 inch (15.8mm) Tool Bit Size: 3/16 inch