With the Rudo USB-A Port Blocker, you can quickly block access to USB-A ports and easily prevent unauthorized data transfer and reducing the risk of data leakage, data theft and computer viruses without permission. The USB Port Blocker is made up of a combined 'key' and 'lock' assembly which plugs into the USB port. To use, simply inserted the key into blocker and slide the button back then pull the key out. With this device, it can physically prevent users unauthorized data transfer, reducing the risk of data leakage, data theft and computer viruses. Package Contents USB-A Port Blocker Key and 5 Port Blockers.