Six final sample tubes were built during the quarterly. Four of these tubes are physically like type FW-267. The other two tubes were also like the FW-267 except the writing gun neck was 3-inches longer to obtain a smaller writing spot size. All tubes contained the improved writing guns, 500 mesh 50-percent transmission collector screens, and 1000 mesh 25-percent transmission backing electrodes. All tubes had a 0.150 inch backing electrodeto-viewing screen spacing.