Features: Working voltages: 2.5V-5.5V. Attention: The power supply voltages should not exceed 5.5V, and the positive and negative terminals of the power supply should not be reversed. Speaker configuration: 4-8Ω, recommended: 4ohm; Speaker power: 2-8W. It can power by computer USB port 5V power supply, a mobile phone charger USB port 5V power supply, or lithium battery power supply. Under high efficiency of 90%, 4Ω load and 5V power supply conditions, it can provide 3W (left channel)+3W (right channel) output power. D-class amplifiers have high efficiency, do not affect sound quality due to temperature rise, and do not require heat sinks, occupying small space. The amplifier board with build-in noise reduction circuit, and there is no popped noise when the power is turned down; The module with shortcircuit overcurrent protections and over temperature protections. Specifications: Material: ABS+Metal Color: Green Size: approx. 20.5x18.4mm/0.8x0.72inch Quantity: 10pcs/set Application: LCD TV, monitors, laptop, portable speaker, portable players, game consoles, mobile phones Package Includes: 10Pcs PAM8403 Digital Amplifier Board Module note: Connect the speaker first and then the power supply, otherwise it may cause damage to the chip. Please allow 1-2cm errors due to manual measurement. Please allow for slight color differences due to different display resolution.