Highly sensitive microphone amplification with ALC automatic level control, providing up to 1000 times amplification to enhance weak sounds. Directly drives headphones for 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, offering 20-30 hours of continuous use when fully charged. For optimal performance, a high-directional microphone is recommendedcan be purchased separately or made independently. 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: 3.5x1.35mm. Dimensions: approximately 6.3 x 5.2 x 2.2cm. Material: plastic and metal. Color: black. Package includes: 1 x amplifier, 1 x charging cable, 1 x phone connection cable. Additional products not included. Note: Lighting effects and display settings may cause slight color variations between the image and actual item. Measurement tolerance: +/- 1-3cm.