3-On-A-Plank Machine Heads (Short)

    "A machine head (also referred to as a tuning machine, tuner, or gear head) is a geared apparatus for tuning stringed musical instruments by adjusting string tension. Machine heads are used on mandolins, guitars, double basses, and others, and are usually located on the instrument's headstock." --Wikipedia

    This type of machine heads are used on classical guitars.