Four Sided Nuts
Square nuts can also be used in a channel or welded to other steel products. 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). They are also much less likely to become rounded-off after repeated loosening/tightening cycles. Square nuts are typically mated with square-headed bolts. Square nuts are used along with flat washers in order to avoid damage from its sharp edges and helps to increase the strength of the fastener.
Square Nuts are available in Stainless Steel, Hot Dip Galvanized and Zinc Plated Steel finishes.