"B3B"is a plating specification the breakdown goes like this. The first letter is the plating material, the middle number is the code number for the plating thickness, and the last letter refers to the final delivery appearance and/or passivation.
This information can be found in our Catalog Section 10 on page 10-1031. In particular the B3B breaks down to :
B (plating material) Cadmium
3 (plating thickness) 8 microns or .0003 inch
B (delivery appearance) Dull matte finish