Protect unused USB Type A ports from unauthorized use as well as dirt and dust. The mounting tool, which also serves as a key for the USB plugs, provides additional security. It reduces the risk of data loss and unauthorized uploading of software or malware. Suitable for IT devices in any office or public environment, such as schools, museums, trade fairs, or other locations. It does not conflict with the existing IT infrastructure and reduces maintenance and control costs for IT equipment. It physically blocks access to a USB port and is quick and easy to use. The set includes 4 locks and 1 key. An optional set of 10 pieces, which includes only USB blockers without keys, is available for separate order.