Features: HiFi Headphone Amplifier, It supports most headphones of high impedance16-300Ω, 3.5mm AUX Input and Output, signal-to-noise ratio> 100Db, THD + N = 0.0003%, fully filter noise, enjoy high-quality audio. Bluetooth 5.0 Receiver,Itis designed to deliver studio-quality sound to your ears through wireless Bluetooth 5.0 technology-suitable for your existing wired headphones, earphones and even speakers. 1500mAH Rechargable Lithium Battery, It adopts a rechargeable lithium battery with 1500mAH capacity, which allows it to stay working more than 8 hours. Plus, there is a volume control knob for volume adjustment. Two-stage Gain Switch, It enhances the signal input into the amp circuit for the optimal performance of the headphones. Make it Possibility to output not only louder sound but a sharper and more Real stereo sound without distortion Broad Compatibility, This amplifier is remarkably compatible with a variety of digital devices, such as MP3, MP4, Mobile Phone, Computer, CD players and personal media player. Specification： Lithium battery capacity: 1500mAH Amp using time: more than 8 hours Bluetooth decoding mode:SBC, AAC Bluetooth protocol: A2DP V1.3.1, AVRCP V1.6 ,HFP V1.7, HSP V1.2 Bluetooth distance: 8m Max Amp battery voltage: DC3.7V - 4V Amp internal working voltage: ±4V SNR>100Db THD+N 0.0003% Adapted Headphone Impedance: 16-300Ω Dimension: 96x61x15mm(L X W X H) Power Output: 16Ω L: 90mw H: 105mw（Gain） 32Ω L: 74mw H: 80mw（Gain） 64Ω L: 45mw H: 50mw（Gain） 150Ω L: 26mw H: 32mw（Gain） Note: For Iphone you are probably required to pair your phone with our headphone amplifier each time. Please follow below: Settings---Bluetooth---My Device, then click "Neoteck RX5.0" to pair. Package Contents: 1 x Bluetooth headphone amplifier 1 x USB Power Cable 1 x 1m Audio Cable 1 x User's Manual