quality power amplifier knapsack 1.Favorable price 2.Any colors and size are available 3.Quick delivery 1, Product Information: Product Name: quality power amplifier knapsackFabric: 600DSize: 42.5*23*30cm, also to be customizedLogo Options: Silk Screen Printing ; Emboidary ; Rubber patch, etc...Parameters:Speaker diameter:57mmAUX input impedance:10-20KΩ output impedance:4ΩFrequency range:80Hz-20 ...