These are a traditional cowrie shell necklace which are worn by both men and women for protective purposes, as well as personal adornment. The leather is made from goatskin; the necklace, so composed, is believed to have medicinal or spiritual value which defend the wearer from whatever he or she may consider to be threatening to them. The clasp for each is the traditional ball and loop style. 

These cowrie shells are the real thing, vintage shells that for centuries prior to European occupation were popular currency in West Africa. Their historical value is still appreciated.

The sizes do vary a small amount but most are approximately 20" (51 cm) in circumference (length, when extended).