Highly sensitive microphone amplification, ALC automatic level control, up to 1000 times amplification, can amplify weak sounds, directly drive headphones for listening, and can be connected to mobile phones for recording, and the interfaces are all 3.5mm;<br> Built-in lithium battery, which can be charged using a mobile phone charger. It can be used continuously for 20-30 hours when fully charged;<br> To achieve good results, you need a high-directional microphone. You can make your own or buy one. Please search online.<br> Input and output interface: 3.5mm;<br> Mobile phone interface: 3.5mm four-pole<br> Microphone gain: 40db/60db switch<br> Headphone amplifier power: 105mwx2/16 ohms<br> Built-in lithium battery, capacity 300mah<br> Power interface: 5V<br> socket specification: 3.5x1.35<br> size: About 6.3 x 5.2 x 2.2cm<br> Material: plastic+metal<br> colour: black<br> Package Contents:<br> 1 x amplifier<br> 1 x Charging Cable<br> 1 x phone connect cable<br> Only the above package content, other products are not included.<br> Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm. Note: 1. Please allow 1-3 mm error due to manual measurement and 1-3g weight error make sure you don't mind before ordering. 2. Due to the lighting of the photos and the difference of monitors, the pictures may not reflect the actual color of the real item. Please make sure you don't mind before ordering, thank you! About Shipping: 1.please pay attention to your delivery address such as: name, street, house number, doorbell/email without name, etc. is correct, or the order will not be delivered correctly. 2.All items will be shipped within 3 business days after the payment is received. Most times you will receive them within 8-12 days then. The specific delivery time is depend on circumstances. 3.During the shopping process, if you have any questions, please feel free to consult us, we will reply you within 24 hours Hope you have a pleasant shopping experience!