Internal interfaces, let you connect to within a PC-housing devices & external are for regular connection from the outside.
Especially
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This patented Hardware drives decoupler set brings your HDD to silence. In this system, two rails are attached Just free in a 13.3 cm (5.25 ") shaft & four rubber pads mounted directly on the hard disk. Thus, there is no direct link between housing & Hard drives, which can be inserted & removed anytime without tools ...

The 38LB electrical safe is useful for storing valuable objects. It is equipped with robust steel plate housing & can be attached to either a wall or a stable surface. It is operated by 4 batteries (type AA). The supplied key can open the safe even when the batteries are empty. ...

Use USB (Universal Serial Bus)-devices like hard-disks, sticks, card reders or also webcams not just at one PC. Print centrally from your multi-purpose printer or easily access music, pictures, data & movies from every PC. You need only a single device & a plug power supply & can still link up to 4 USB (Universal Serial Bus) devices in your network with a transfer rate of up to 1000 MBit/s. The access of several users to one & the same device does not take place simultaneously, but instead one by one & is regulated by the accompanying software. Two different users can simultaneously access two different USB (Universal Serial Bus)-devices. The massive pedeatal provides for s secure position, even when all the cables are connected. The sleet design is perfect for cramped spaces. ...