Rockville ONE-TOWER BG all-in-one Bluetooth tower speaker system with HDMI, Optical, RCA. For home use Must be plugged into an outlet during use. Built In Bluetooth 5.0 chipset with 33 foot range and clear sound quality. Built in USB playback (up to 32GB). (2) 4 woofers and a rear port for extremely loud and clear bass response down to 32Hz. (2) 4 full range drivers with polypropylene cones handle the highs and mids. Rear port is tuned to 35Hz and delivers clear bass response.