-let μmToInch(x: float<μm>) : float<inch> = x / μmInchRatio
-let inchToμm(x: float<inch>) : float<μm> = x * μmInchRatio
+let μmToInch(x: float<μm>) : float<inch> = x / μmPerInch
+let inchToμm(x: float<inch>) : float<μm> = x * μmPerInch
+
+let mmToInch(x: float<mm>) : float<inch> = x / mmPerInch
+let inchTomm(x: float<inch>) : float<mm> = x * mmPerInch