This inlaid brass bracelet is just one of the many versions of the bracelets that Tuareg people still make and use themselves. They say the inlays are "ebony" but I sincerely doubt that, and can't say what that black inlay really is. Perhaps traditionally they were ebony.

This bracelets measure: 2 5/8 x 2 1/8" (6.8 x 5.4 cm) with a 15/16" (2.4 cm) opening. The interior dimensions are 2 7/16 x 1 7/8" (6.2 x 4.8 cm)