Freud 15 mm (Dia.) Cylinder (Hinge) Bit CB15057R Tie-Wire Wedge Anchor What are the optional triangle

What are the optional triangle holes on the HU410SS used for

Bore Diameter (F) 6mm

this heavy-duty mill combines a pneumatic power drawbar

2 square inches (129 square millimeters)

Freud 15 mm (Dia.) Cylinder (Hinge) Bit CB15057R Tie-Wire Wedge Anchor What are the optional triangleDiameter: 15mm Length: 57. 5mm Shank: 10mm Rotation: RH Tools: Drill Press; Hand Held Drill Materials: Composites; Solid Surface; Veneered Plywood; Hardwoods; Softwoods These boring bits are designed for accurate boring and the two wing cutters and two spur cutters prevent bottom side tear out. Boring bits are supplied with a 10mm shank with an adjustable top screw making them compatible with most boring machines. The 3557E is designed with a 3 8"