Highly sensitive microphone amplification with ALC automatic level control, providing up to 1000 times amplification to enhance weak sounds. Directly drives headphones for real-time listening and supports connection to mobile phones for recording. All interfaces are 3.5mm. Built-in lithium battery can be charged using a standard mobile phone charger. Offers 20-30 hours of continuous use when fully charged. For optimal performance, a high-directional microphone is recommended. Compatible microphones can be purchased or custom-built—please search online for options. Input and output interface: 3.5mm Mobile phone interface: 3.5mm four-pole Microphone gain: switchable between 40dB and 60dB Headphone amplifier power: 105mW x 2 at 16 ohms Built-in lithium battery capacity: 300mAh Power input: 5V Socket specification: 3.5 x 1.35mm Dimensions: approximately 6.3 x 5.2 x 2.2cm Material: plastic and metal Color: black Package Contents: 1 x amplifier 1 x charging cable 1 x phone connection cable Note: The package includes only the items listed above. Other accessories are not included. Note: Lighting effects and display differences may cause slight variations in color between the product image and the actual item. Measurement tolerance is +/- 1-3cm.