In ancient Egyptian religion, Menat (ancient Egyptian mnj.t, modern Arabic منات) was a name of the goddess Hathor, and of a type of artifact closely associated with her, much like the sistrum was.
The artifact, whose name was slightly different in hieroglyphic spelling than that of the goddess, was held in the hand by its counterpoise and used as a rattle by Hathor's priestesses. Often it was worn as a protective amulet, even by Apis bulls.
Part of the menat was a plate called an aegis (Greek for "shield"), worn on the chest, to which strands of beaded strings were attached. The other ends of the strings were tied to a counterweight which dangled on the wearer's back. The aegis was often made of faience, but other materials as varied as leather and bronze were also used. It was often inscribed or bore depictions of deities associated with Hathor.
The necklace was meant to ensure good luck and fortune and to protect against evil spirits. It was also worn for protection in the afterlife and is often found buried with the dead, given as a grave gift since Ramesside times (the Nineteenth and Twentieth Dynasties that comprise the last two-thirds of the period known as the New Kingdom). Worn by women, it was expected to foster fruitfulness and good health, while among men it signified virility.
Media related to Menat-necklace and counterpoise at Wikimedia Commons