A universal serial bus device and a USB system are provided. The display panel module includes a display panel; a first casing having a hollow region; an addition member arranged on the first casing; a first adhesive member having one side attached on the first casing, another side attached on the display panel and a breathing structure; and a second casing coupled with the first casing to fix the display panel therebetween. The compounds of the present invention display good level dyeing properties, good build up and excellent low nylon cross-dyeing. The backrest assembly may be configured to swivel with rotational movements around at least one axis of rotation. A compressed portion extends from the lower end of the fixed holding portion. The equalizer may include a filter circuit, and a filter control circuit.