speaker backpack earphone 1.Favorable price 2.Any colors and size are available 3.Quick delivery 1, Product Information: Product Name: speaker backpack earphoneFabric: 600DSize: 50*21*37 cm, 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 KHzSpeaker ...