Diaphragms were invented in the mid 1800s and peeked in popularity around the 1930s. Then, with the rise of hormonal contraceptives and the pill, diaphragms fell into oblivion. Although they are one of the few female-controlled and extremely low-risk birth control options, many women view this form of birth control as old fashioned, or don't even know it exists.
The traditional diaphragm developed very little during its life, the circular device covers the cervix to prevent sperm from entering the uterus.
Better and more comfortable springs and the transition to silicone over latex did improve on the basic functioning of the device. The Janssen owned Ortho branded All-Flex diaphragm may have been totally removed from the market recently, and we understand that the Reflections diaphragm will soon be withdrawn as well.
Sizing across diaphragm brands is compatible. For example, an All-Flex user with a prescription for a 70mm diaphragm could use a 70mm Milex Omniflex diaphragm. The Cooper Surgical owned Milex brand diaphragm is still in active production.