CD Indicator
Indicator developed by Adolf Schmid, Vienna, 1931.
Based on the discovery of the fertile and infertile days by gynecologists Hermann Knaus (Austria) and Kyusaku Ogino (Japan), Adolf Schmid developed an instrument to determine fertile and infertile days.
The small device was produced in Switzerland and was successfully sold throughout the world. With the advent of the Pill, sales declined in the 1960s and finally led to the cessation of production.