Square nuts, Hot dipped galvanized steel

Nut size (A.K.A. diameter) is the size bolt that the nut is used with. The same is true of the thread count. Thus a 1/4"-20 nut fits a 1/4"-20 bolt.

Important Note: Due to the plating thickness, only hot dipped galvanized bolts should be used on hot dipped galvanized nuts.