Our samll diameter spline lug bolts are made by high quality alloy steel, diameter is only 20mm, available for wheel with small diameter recesses. We offer 10.9 grade normally, rockwell hardness is HRC32-39.
Besides, spline lug bolts are a kinds of spline anit-theft key, protecting wheels from theft, more safty to use.
HONISHEN brand chorme bolts pass over 72~200 hours neutral salt spray (NSS) testing, and black chrome bolts pass over 96~500 hours NSS testing.
The matched key passed over 72-hour heat treatment and hydrogen treatment. Not only the hardness reach to HRC38-42, but also it's ductility can be ensureed and prevent craze.