An early version of a bell-shaped menstrual cup was patented in 1932, by the midwifery group of McGlasson and Perkins.[31] Leona Chalmers patented the first usable commercial cup in 1937.[32] Later menstrual cups were patented in 1935, 1937, and 1950.[33][34][35] The Tassaway brand of menstrual cups was introduced in the 1960s, but it was not a commercial success.[36] Early menstrual cups were made of rubber.[14]