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.

The term "jam nut" can also refer to any nut that is used in the same function (even a regular-thickness nut used for the jamming purpose). Jam nuts, other types of locknuts, lock washers, and thread-locking fluid are ways to prevent vibration from loosening a bolted joint.

Jam nuts are also known as:  half height nuts, hex thin nuts.  Jam nuts are used without lock washers when jammed against another nut, and may be used with lock washers when installed as a single nut.

Size: M6-M48

       other sizes are available upon request

Width across flats: as per size

Width across corners: as per size

Thread type: metric corse/fine right-hand thread

                     imperial thread is available upon request

                     left-hand thread is available upon request

Material: steel

Grade: 4.8/6.8/8.8/10.9/12.9

Finish: plain/black oxide/zinc plated (galvanized)/hot dip galvanized (HDG)

           other kinds of surface treatment are upon request

Technical info: DIN 439/DIN 936