5/16"-18 Zinc Plated Steel Coarse Thread Square Nuts

Diameter: 5/16"
Thickness: 17/64"
Material: Steel
Finish: Zinc
Driver Type: 9/16" Wrench
Thread Size: 18 (Coarse)
Type: Square Nut

Box of 20.

A square nut is a four-sided nut. Compared to standard hex nuts, square nuts have a greater surface in contact with the part being fastened, and therefore provide greater resistance to loosening (though also greater resistance to tightening). Square nuts are typically mated with square-headed bolts.