A chemist might read this as Antimony Bismuth.

Antimony was called Stibium, hence the Sb.

Atomic numbers are Sb 51, and Bi 83.

According to Wikipedia, Bismuth is a pentavalent post-transition metal and one of the pnictogens with chemical properties resembling its lighter homologs arsenic and antimony.

The periodic table contains a couple more SB’s: Selenium Bromine, Strontium Barium and Seaborgium Bohrium.