Product Description Features: 1. All kinds of mouse can be used smooth on the slippery surface of mouse pad. 2. Extend USB ports can connect to any USB peripherals. Such as MP3, U disk, DC, Mouse etc. 3. Inside dimensional speaker, can listen music from computer. "ON/OFF" switch for open and close the sound, for press "PTT" button for shut the sound. 4. Inside high sensitive MIC, also have "PTT"(push to talk) function, press "PTT" button while talking and free for listening. 5. Speaker jack and MIC jack can connect extra speaker (earphone) and microphone. USB 2. 0 HUB. (2 Ports) SD/MMC Card Reader. Insert direction according arrowhead silk-print PTT SYSTEM USB1.1 HUB(4 Ports) PTT SYSTEM USB2.0 HUB(4 Ports) PTT SYSTEM