Recommended transformer voltage for DC 12-18V, the battery can also be Oh, positive and negative automatic identification, do not worry reversed. Many of our family router power idle most of them can be used, the current size of the power output, 1A is the most basic requirement, 2A or more on relatively good. Casual use of other power supply specifications may cause burn! PCB size: about 7.60*1.90cm/2.99"*0.75" 7.60*4.70cm/2.99"*1.85" Speaker package: The main channel 10W + 10W 3-5 4-8 Euro 10-30W inch full-range or high speakers Heavy 20W 4-6 inch 4-8 European 10-40W subwoofer We recommend 2-4-inch full-range 4-6 inches is more appropriate choice with inappropriate or horn speaker box is not even installed it certainly is not effective speaker identification method is a magnet to a large, off to circle stiff, box should be strong, sealed box maze conditional use, wall paste sound-absorbing cotton, can be obtained relatively pure solid Note: Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Package List: 1kit x TDA7377 amplifier board