Back then, nuts were commonly made with a simpler square head as they were easier to manufacture. However, due to the found advantages of hexagonal nuts or hex nuts, they became more popular.

From the name itself, a hexagonal nut is a nut with a hexagon-shaped head. Threads of the hex nut are either right-hand or left-hand. The size of hex nuts refers to the nominal thread diameter, which is typically from ¼” to 2 ½”. 

Hex nuts are used with other fasteners such as bolts, threaded rods, anchors, studs, or screws. Other fasteners may also be used along with it.

Using hex with other fasteners need careful installment to ensure full thread engagement. When using with bolts or screws, make sure that either of these two is long enough that there’s two more full threads beyond the nut face once it’s tightened.