and high quality The power supply voltage is 2.5-5.5V, more than 5.5V, the chip burn out.The power supply current recommended 1A or more, less than 1A sound be small. The positive and negative poles of the power supply can not be reversed, and the reverse chip is burnt.The load recommended 4 Euro 3W speakers. This module has a mute switch, high level mute, low level playback, the default is low level playback. This module is suitable for amplifying the audio signal of 0.5V-1V. If the signal is too small, it needs to be connected to the preamplifier.This module is only suitable for single-supply operation and cannot be connected to a negative power supply. Specification: Working voltage: 2.5-5.5VDC Working current: 1A or more Output power: 3-5W Load parameters: impedance 4-8 Ohm, speaker power 3-5W Signal to noise ratio: 85dB@ =5V, Vorms=1V Dimensions: 1.2x1.5cm/0.47x0.59 inch Quantity: 2 Pc color: blue Material: plastic + metal Package Contents:2 * Digital Amplifier Board Only the above package content, other products are not included. Note: Light 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.