This is a shorter choker-length version of a quintuple amulet (5 pendants) - known generically in Africa as a gri gri. It is also commonly called a good luck charm. As such it is worn, by both genders for protection, as well as personal adornment. The leather is made from goatskin and each little pillow would have carried something of medicinal or spiritual significance to the owner, possibly a koranic verse which would defend the wearer from whatever he or she may consider to be threatening to them. Ours are just filled with paper. Cowrie shells, prior to European occupation, were currency and so still reflect a certain value. These cowrie shells are the real thing, vintage shells that were in use for centuries. 

 The choker circumference is 16 1/4" (41 cm)