McMaster 90725A740 Zinc-Plated Steel High Hex Nut Class 8, M20 x 2.5 mm Thread PK5

Slightly taller than standard-profile hex nuts, these have a larger gripping area so your wrench or socket won’t slip off as you tighten them. They’re often used in vehicles and machinery where fasteners can be difficult to reach.

Medium–Strength Steel—These Grade 5 or Class 8 nuts are your go-to for fastening most machinery and equipment. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Zinc–Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.