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 3/4 x 2 1/4" (7 x 5.7 cm) with a 1 9/16" (4 cm) opening. The interior dimensions are 2 9/16 x 1 3/4" (6.5 x 4.4 cm)