2 SPEAKERS IN EACH EAR CUP PROVIDE TRUE 2.1 SOUND; FREQ RESP: 20 HZ–30 KHZ; DECODES DOLBY® AC3, PROLOGIC® II, DTS & AAC; UNCOMPRESSED AUDIO FOR CD-QUALITY MUSIC & EXTRA VOICE CLARITY; 7.9 OZ FOR MAXIMUM MOBILITY; PADDED, SELF-ADJUSTING HEADBAND FOR COMFORTABLE, CUSTOM FIT; UP TO 12 HOURS OF BATTERY LIFE WITH INCLUDED LI-POLYMER BATTERY; INCLUDED DUAL POWER TRANSMITTER RUNS WITH INCLUDED AC ADAPTER OR REQUIRES 3 AAA BATTERIES