Flanged Lock Nuts, Range of Sizes

Flange Lock Nuts have the shape of attached washer at one end of the Hex Lock Nut. Flange Lock Nuts provides the extra resisting surface to add to the tightening strength to the nut. Sometimes, flange lock nuts are used to cover oversized holes or bridge elongated slots. 

Flange nuts cover more area when used on oversized or irregular shaped holes as the ring attached to the nut end provides more circumference.
Flange lock nuts provide more space for serration. Serration is the process of putting irregular surface to increase the resistance force between the surfaces. As there is more mating space, it provides more tightening strength.

No need to put washers when using flange lock nuts and it also cuts the extra cost of washer and time when applied in applications.