With this neat little device, system administrators can physically prevent users from connecting pen drives, MP3 players and other USB mass storage devices to their computers to copy data, introduce viruses etc. The USB port blocker is made up of a combined 'key' and 'lock' assembly which plugs into the USB port. To use, simply plug the 'keylock' into the port and release the latch - the lock remains in place! Plug the key back into the lock to remove. Easy!