The pack of ten XK-A-556-R X-Keys Key Blockers from XKeys take place of any single key on an X-keys XK series device and leave a flat surface at the case top for a professionally finished look. These key blockers friction fit into the XK series deck and may be removed or swapped with keycaps to modify or update a key configuration. You can use these blockers to create a custom layout for your applications. The blockers let you separate keys into groups by function.