Stereo Sound on the Go - Purple Philips Portable Speaker - Pocket-sized and Powerful - 40 Hours of Continuous Play for Worry-free Enjoyment The durable, lightweight material and design mean you can carry the speakers with you wherever you go. Battery powered for portability - 40 hours of continuous play for worry-free enjoyment Universal: works via your device's 3.5mm headphone jack, Line-in cable becomes a lanyard for easy portability Class 'D' digital amplifier for quality sound performance, Mobile phone shielding technology for static-free sound Frequency response: 350 - 16,000 Hz, Impedance: 4, RMS Power rating: 2 W, Battery type: AAA (Batteries not included, best with Polaroid AAA batteries)