The Capaci-Tester CT-1 came on the market in 1957. In 1963 it was replaced by the IT-22 and was produced until 1967. The CT-1 and the IT-22 are practically identical. It is a simple instrument to check whether a capacitor is "open", "shorted" or "OK".  An electron beam tube or "magic eye" is used for the read-out indicator.