The minimum allowable bare steel thicknesses and their mil designators are as follows: 25 Gage - .0179" = 18 mil 22 Gage - .0269" = 27 mil 20 Gage - .0329" = 33 mil 18 Gage - .0428" = 43 mil 16 Gage - .0538" = 54 mil ... 7 |% [) \) k" }" z3 o/ G v 0 ], x. \( h: l18 gage steel 也就是43 mil 规格的钢。mil 千分之一寸。