A calculation disc for indication of fertile and infertile days. The method is based on the findings of Hermann Knaus and Kyusaku Ogino from the 1930´s.
Knaus and Ogino were the first in human history, who managed to correctly identify fertile and infertile days. This counting device can be used with 28-days´cycles only. The calculation disc was produced and sold by a Styrian company for each new calendar year.
Inscription KONZIP. Patented in all states, regulated prize 2,50 Schilling. Contraceptive calendar for women, round disc with the first day of menstruation and the fertile days for the year 1932, includes a calendar and opportunity to mark „beginning of menstruation“ (see also object number 1008)