The rated working voltage is 2.5V - 5V, and the limit working voltage is 5.5V. Ultra Mini Size: 21 x 18 x 3.4mm(L x W x H). Various digital products can be easily placed in a small space for efficient amplification; double-sided wiring can properly solve the wiring caused by potential balance and crosstalk between channels Two-channel stereo, 5V power supply can output 3W+3W power, can directly drive 4Ω, 8Ω small speakers, the output power is large, the energy is sufficient, and the sound quality is good. Excellent noise suppression, no audio input with ears close to speakers, no noise can be heard; unique Class D digital powerless board with LC filter can be powered directly from the computer's USB. For any DIY design that requires a miniature audio amplifier, especially battery powered portable and mobile applications. Colour:green Material:ABS Package Contents: 10 x Digital Power Amplifier Board Only the above package content, other products are not included. Note: Light shooting 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!