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.
Supplemental DHEA will increase androgen (male sex hormone) levels in women; and at some dosage women will experience the effects of this. At doses above 100 mg. per day these androgen effects may begin to show up in things such as increased facial hair. These effects are slow to develop and reversible, though.