Fostex PM0.1 Personal Active Speaker System, Set of 2, Black (PM01B) 2.2-inch full range driver with fiberglass diaphragm for clear sound reproduction Wooden enclosure for a natural sound Rear bass reflex enclosure boxes for well-balanced low frequencies Automatic energy saving function switches to sleep mode after approximately 15 minutes of no signal input Pairs with model PM-SUBmini (sold separately) to add extra lower bass for movies and live music performance video playback