Four (4) RJ keystone opening knockouts. Use as blank plate or for up to four (4) RJ openings. NOTE: For RFB4 Series Floor Box side compartment only. Opening dimension is 9/16'' x 3/4'' ( 14.3mm x 19.1mm). For use on tile, terrazzo, carpet, or wood covered floors. Additional configurations available. Please consult your local Sales Representative for information.