1. 16-300Ω Mini HiFi headphone amplifier, It is delicate, compact, , and portable that it can be carry conveniently. 2. 3.5mm AUX input and output, SNR 100Db and +N 0.0003%, possibility to output not just louder sound, but a and more real stereo sound without distortion. 3. Two-stage gain switch enhances the signal input into the amp circuit for optimal performance of the headphones 4. Aluminum matte , fashion design provides you a comfortable handheld feeling while the aluminum matte makes it . 5. Rechargeable lithium battery, it adopts a rechargeable lithium battery with 1000mAH capacity, which allows it to stay working more than 8 hours. Universal compatibility, it can remarkably compatible with a various of digital devices, such as MP3 MP4 mobile phone computer. HiFi headphone amplifier, delicate, compact, , and portable, which convenient to carry, can output sound without distortion. Lithium battery capacity: 1000mAH Amp using time: more than 8 hours Amp battery voltage: DC3.7V - 4V Amp internal working voltage: ±4V SNR 100Db +N 0.0003% Output Power: 40Mw in Impedance 16Ω Adapted Headphone Impedance: 16-300Ω Dimension: 95 x 52 x 13mm(L x W x H) Color: Black Material: ABS Package Contents: 1 * Headphone amplifier 1 set * accessories Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.