This USB sharing switch is to share a USB device like printer, scanner, HDD storage, etc for four computers via USB connections. 
<br />And you can shift via hot key (Ctrl+F11) from one computer to another to use the external USB devices. 
<br />It's USB powered and no external power adapter is needed. 
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<br />* 100% brand new and high quality
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<br />* Surface Material: Plastic
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<br />* USB1.1/2.0 Compatible
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<br />* 4 USB B-Type ports to computers
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<br />* 1 USB A-Type hook-up to USB device
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<br />* USB bus powered
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<br />* 4 LED indicators
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<br />* Support USB devices like printer, scanner, HDD storage, etc
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<br />* Auto switch on computer to share the USB devices among two computers
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<br />* Window 2000/XP/Vista/Windows7 32bit/64bit, MAC OS supported
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<br />* Weight: 62g
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<br />* Dimension:aprox 100mm x 50mm x 20mm 
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<br />Package Includes:
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<br />*  1x 4 Port Auto USB Share Switch Box 
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<br />* 1x  cd driver