Highly sensitive microphone amplification with ALC automatic level control, providing up to 1000 times amplification to capture 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, offering 20-30 hours of continuous use when fully charged. For optimal performance, a high-directional microphone is recommended—available separately or can be self-sourced. 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. Charging 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. Product does not include any additional items not listed. Note: Lighting effects and display settings may cause slight variations in color between the image and the actual item. Measurement may vary by +/- 1-3cm.