This wider version of the inlaid brass bracelets 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 bracelet measures: 2 1/2 x 2 1/4" (6.4 x 5.7 cm) with a 1 1/8" opening (2.9 cm).