The slots are for the insertion of a cotter pin to secure the nut when used with a drilled shank fastener

The nylon flange head adds stability in hollow surfaces

1-8 x 12 Grade 5 Hex Cap Screw Zinc Plated

3/4 x 7 Titen HD Concrete Anchor Zinc Plated (5)

1-14 x 4 1/2 Grade 5 Hex Cap Screw Zinc Plated

2-8 A194 2H Heavy Hex Nut Plain 7/8-9 Grade 5 Hex Cap Screws Zinc Plated The slots are for the2 8 A194 2H Heavy Hex Nut Plain . A194 2H Heavy Hex Nuts are manufactured from 1045 steel to meet or exceed ASTM A194 Grade 2H. Hot Dip Galvanized material will meet or exceed ASTM A153 and or ASTM F2329. Galvanized nuts are over tapped per ASTM A563. Typical hardness is HRC 24 35 for diameters up to 1 1 2 inches, HRB 95 HRC 35 for diameters over 1 1 1 2 inches. Proof load strength is 175,000 psi.