Hexagon Thin Nut

Hex thin nut are thinner than a standard hex nut but have the same dimension across the flats and corners.  Hex thin nuts have two common applications.  A thin nut can be threaded onto a bolt and run tight against the standard nut which will lock the nut in place and prevent it from backing off.  hex thin nuts are sometimes used for leveling purposes as well.

Since hot-dip galvanizing typically adds 2.2 to 5 mils of thickness to the threaded portion of a fastener, galvanized hex thin nuts are tapped oversize to compensate for the corrosion resistant coating on the bolts.