Leviton calls these "QuickPort" inserts. Others would know them as "keystone." Both names are trade names and are somewhat interchangeable. (May have slight fit or appearance issues.) Most useful due to their "building block" nature, a QuickPort frame can hold many QuickPort inserts, which come in a variety of connector styles and colors. The user can configure a wall plate or rack panel with the exact connectors they need.
