Charleston slave badge from 1806 for Porter No. 36

This is an octagonal metal slave badge broken across the middle into two halves. The recto of the top half (a) has text that reads ”CHARLESTON [stamped]” across the top. Under that is “No. [stamped] 36 [punched].” After the number is an incised “X”. The recto bottom half (b) has text that reads “PORTER [stamped] / 1806 [stamped].” On the verso bottom (b) is a stamped cartouche at the bottom center with the word “C PRINCE.” There is a hole punched at the center top.