The sistrum was an ancient musical instrument, kind of like a rattle in shape combined with the idea of a modern tambourine. It had two basic designs, the naos and the hoop. Most late period were of the hoop design. Most commonly it featured a representation of Het-Hert (Hathor) on the handle. It was used in sacred rituals, most particularly for Het-Hert but later associated with Imen (Amun) and Aset (Isis). It was most particularly used by the women musicians and chantresses who served in the temple, and the sound was believed to ward off the powers of chaos.