Cardboard box containing 4 x 4.5 inch Image Orthicon tubes. Types included are: 9387; 9295C; 1938.

The 4.5 inch IO (Image Orthicon) tube was developed in the UK - based on the RCA-developed 3 inch tube it gave much improved resolution and better picture shading. Although less sensitive than the 3 inch version it rapidly became the mainstay of monochrome broadcast cameras. The Elcon target was much better than the earlier soda-lime targets and was less prone to "image sticking".