ENABLES YOU TO FEEL YOUR BEATS - The ZM-2 Module has a haptic subwoofer that provides tactile rumble. It utilizes vibrotactile feedback and psychoacoustic technology to let you hear bass frequencies OFFERS ADJUSTABLE RUMBLE LEVELS - You can increase/decrease the output levels of the rumble. You can also turn it off completely by setting it to the lowest level PROVIDES A SILENT METRONOME - The additional feature makes sure you're fully aware where the beat is at OP-Z at all times. It helps keep you in time, especially during live performances PROVIDES MAXIMUM IMPACT - The 10Hz-150Hz frequency response increases the overall physical impact while minimizing energy consumption EASY TO INSTALL AND KEEP IN PLACE - Remove the OP-Z' backplate and replace the dummy module with ZM-2. Plus, Rumble's lock switch ensures the module is safely inside the OP-Z always