How to select black nuts?

Normal black nut have 2 kinds, one is black electrophoretic nut, the other is black chrome nut.

1.How to distinguish two kinds of black nuts

Compare inner hole of nut:  

black electrophoretic nut, black in appearance and inner hole

Black chrome nut,  appearance is black, but inner hole is silver.

2.Which black nut is better?

3.We recommend black chrome nut if nut is close end type.

4.If nut is open end type, we recommend do black electrophretic coating, because open end nut will show the silver hole, it will impact the beauty if nut placing on wheel