2-CHANNEL SELECTION TO ACHIEVE BEST POSSIBLE PERFORMANCE. PHASE LOOP LOCK CIRCUITRY AUTOMATICALLY LOCKS IN & KEEPS AUDIO SIGNAL CLEAR & STRONG. 900 MHZ TRANSMITTER SENDS AUDIO SIGNALS WITHOUT SPEAKER WIRE. RCA INPUTS FOR HOME THEATER RECEIVERS, MP3 PLAYERS, COMPUTERS & IPOD. 20W RMS POWER. 5.25" POLYPROPYLENE CONE WOOFER WITH RUBBER EDGE. 2" MYLAR CONE TWEETER. FREQ RESP: 40 HZ 2 KHZ. WEATHER RESISTANT FOR OUTDOOR LISTENING. PLACE SPEAKERS UP TO 150 FT AWAY FROM AUDIO SOURCE. COMPATIBLE WITH ALL AUDIO UNLIMITED PRODUCTS TO COVER LARGER AREAS. DIM: 13"H X 10"W. INCLUDES RECHARGEABLE LI-ION BATTERY. .