As correctly pointed out by ASimpson, there are classification of fits which are application specific. He lists the metric version, imperial are equivalents noting 1.0 inch = 25.4 mm. There are several good references on this, look to the web. But the Machinist Handbook does discuss this, at least in the 23rd edition.
How does Dhea work? DHEA is a parent hormone produced by the adrenal glands near the kidneys and in the liver. In men, DHEA is also secreted by the testes. It is changed in the body to a hormone called androstenedione. Androstenedione is then changed into the major male and female hormones.
How DHEA Works. In 2004, CHR became the first IVF center to introduce DHEA into fertility treatment. Since then, DHEA supplementation has demonstrated remarkable results worldwide. In fact, in a 2010 survey, a third of all IVF centers in the world reported prescribing DHEA to improve pregnancy chances in women with diminished ovarian reserve (DOR).