The gravikord is a modern, 24 string, electric double bridge-harp invented by Robert Grawi in 1986, which is closely related to both the West African kora and the kalimba. It was designed to employ a separated double tonal array structure making it possible to play cross-rhythms in a polyrhythmic musical style in a modern electro-acoustic instrument. There is a similar instrument, also developed by Grawi, the gravi-kora, which is tuned identically to a traditional 21 string African kora.