Features: brand new and high quality Mini high-fidelity headphone amplifier, easy to carry, can output excellent sound without distortion. Amplifier use time: more than 5 hours, load impedance: 16-300Ω. The two-stage gain switch can enhance the signal input of the amplifier circuit to achieve the advanced performance of the earphone. 3.5mm AUX input and output, SNR>120dB, distortion 0.004%, not only can output a louder sound, but also a clearer sound.for MP3, MP4, mobile phones, laptops and 3.5 mm audio and various digital devices. Lightweight Size: Portable and small size, easy to store and carry, bring you convenience. Specifications: Material: Metal Color: Black Product Dimension: approx. 2.4x1.2x5.31inches Net Weight: 95g/0.21lbs Package Includes: 1PC Portable Headphone Amplifier Hifi Audio Amplifier note: Please allow 1-2cm errors due to manual measurement. Due to the difference between different monitors, the picture may not reflect the actual color of the item.