Jam nuts are thinner than standard nuts and thread against a primary nut to lock it in place and prevent loosening.

Nominal Size: 3/4"
Thread: 10 TPI (Coarse)
Width Across Flats: 1-1/8"
Height: 27/64"
Across-Corners Size: 1-1/4"
Material: Steel
Finish: Zinc
Shape: Jam Nut
Type: Jam Nut
A jam nut is a low profile type of nut, typically half as tall as a standard nut. It is commonly used as a type of locknut, where it is "jammed" up against a standard nut to lock the two in place. It is also used in situations where a standard nut would not fit.