Use this SY-ACC20165 port blocker to prevent other devices from being connected to the system. Keep out devices such as Pen Drive, Mass Storage Devices, Cell Phone Adapters, and more. The port blocker includes a "key" which is used to lock in and remove the USB blockers. - USB Port Blocker: 4 Red - Physically blocks the USB ports to deny access to the USB ports - Includes: 4 locks and 1 key