Driver Type: 1-5/16" Wrench
Thread Size: 9 (Coarse)
Type: Square Nut
Box of 6.
A square nut is a four-sided nut. Compared to standard hex nuts, square nuts
have a greater surface in contact with the part being fastened, and therefore
provide greater resistance to loosening (though also greater resistance to
tightening). Square nuts are typically mated with square-headed bolts.