rockville rvd9bgb black/grey/beige 9" dvd flip down car monitor, hdmi+headphones rockville b channel, ir_out_r:3.2mhz. sensitivity 96 db. modulation high frequency. power supply 2x1.5v. battery r03 (aaa) 48h (batteries not included). weight 160 gr. (excl. bat teries) these are dual channel headsets which means you can use multiple of these at the same time while having each headset listening to a different source. if you have dual dvd headrests, or video games built into one of your monitors, then this is the best solution for you.