there is a square-shaped section that prevents the bolt from rotating when tightened

2-5/8" SHARK HOLESAW

2-1/2 in Pressure Rating Sch 40 Schedule Rating 40

50X25MM SS HEX CAP SCREWS [500/BX]

STANDARD BI-METAL RECIP BLADE 9"

1" S&D 1/2 RS DRILL there is a square-shaped section1" S&D 1 2 RS DRILL Silver & Deming style drill bits, 118 point. Made from M35 steel with 5% cobalt, Centurys Cobalt drill bits are designed to cut through extremely hard metals, including stainless steel. Polished finish for fast chip removal, keeping the bit cool and reducing wear. Cobalt steel will remain sharper while drilling large diameter holes in ferrous and non ferrous steels and other materials where large diameter holes are required.