Magpul Heat-Treated Castle Nut

The Heat-Treated Castle Nut screws onto the AR15/M4 lower
receiver extension (buffer tube) and keeps the receiver extension and lower
receiver end plate secured in place.  The
large notches allow for positive engagement with a castle nut wrench for proper
installation and torque.  The smaller
notches provide a location for the end user to stake the castle nut to prevent
accidental loosening.

Finished in a Mil-spec manganese phosphate.

Made in the USA.