... 4.ATC testing ,CE certificate,ISO9001:2008 VCOM Professional Mini Speaker Product Feature: Frequency:150~18KHz Imdedance:4Ω Distortion ... : Determined by the volume and songs, the normal volume of 1-2 hours Support for:mobile phone/MP3/MP4/Laptop ... Board.Categories of computer electronics: Headphone, Bluetooth Headphone, Earphone, Speaker, Mouse, keyboard,Game Headphone and Keyboard, Game Mouse, Gamepad ...