This motor drives a 3" diameter 8-Layer Flat Wire Aluminum Voice Coil wound on a thick aluminum former to incredible levels of excursion. The Z v.6 now uses the same voice coil as the NS v.5 series. The Z v.5 utilized a 4-layer voice coil – the change to an 8-layer was to answer our customers desire for higher motor force (more output) and it does just that!