This cuff bracelet is one of the best 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).