HO Diaphragm for 1 MDC/Roundhouse/Athearn Harriman car. Black only. Close the gap with our innovative injection molded operating diaphragms. This easy to assemble kit turns a string of passenger cars into a train. Diaphragms stay connected in turn radii over 24 inches and have no minimum radius for smooth operation. Diaphragms are designed for Kadee #5, Intermountain and McHenry couplers unless otherwise noted. Instructions are included with all kits.