SONY SRS-P7 Passive Portable Speaker System SRSP7 Supplying a soundtrack to those hours of due diligence in the study carrel, waiting in line for tickets, or hard-fought hackeysack tourneys, requires only your Walkman and the SRS-P7 Passive Portable Speaker System Bass reflex duct design provides amazingly powerful sound with lots of bass end "Passive" means no Batteries or plug-in required Stereo mini-plug Input Speakers join together into a lightweight, easily carried package Driver units: 2-inch diameter cones Impedance: 6 Ohms Sensitivity: 83dB/w/m Frequency response: 250Hz>15kHz Dimensions (Each Speaker): 4-1/4"H x 2-7/8"W x 2-5/8"D; L&R speakers together weigh 9-1/3 ounces Color: Silver