Features: 1) Suitable for MP3, MP4, CD, notebook, PC, PDA, PSP, mobile phone and other digital products with audio frequency output 2) With unique anti-traditional design, the power amplifier, batteries and double loudspeakers are all collected in the egg-sized sound box body 3) The originally patented retractable resonator has solved a difficult problem of too small resonator of mini sound box 4) The dimension limit of sound boxes has been decreased to the minimum 5) Loudspeaker output: 2W 6) Sensitivity: 85?dB 7) Distortion: 0.5% 8) Lithium ion battery output: 3.6V 9) Lithium ion battery input: 4.2?.05V 10) Dimensions (L x W x H): 45 x 57 x 35mm (without audio plug nor retractable resonator) 11) Weight: 60g (including batteries) 12)Certification: CE&FCC&ROHS