6 sealed machine heads(3L + 3R). Compatible with electric or acoustic guitar. With internal gear. Material: zinc alloy Speed material: copper Color:Black Package Contents: 6 * Machine Heads 6 * Mounting screws 6 * Ferrules 6 * Threaded sockets Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real . The measurement allowed error is +/- 1-3cm.