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.
1 DHEA supplements may interfere with other medications thus you should take it only under medical supervision. 2  If you're under the age of 40 and have normal DHEA levels (at least 130 mg/dL for women and 180 mg/dL for men) then DHEA supplements is not for you. If you're under the age of 40 and have normal DHEA levels (at least 130 mg/dL for women and 180 mg/dL for men) then DHEA supplements is not for you. 2  When taking DHEA you should monitor your blood levels every 6 months. 3  So far, there's still no reliable study on the long-term safety use of DHEA.