This European Standard specifies the dimensions, tolerances and the required characteristics of a fitting end, 24° cone, external thread, flareless type, size -04 up to -20 for use in hydraulic and fluid systems at 5 080 psi, diameter 1/4 inch ≤ D ≤ 1 1/4 inch (6,35 mm ≤ D ≤ 31,75 mm) for aerospace applications.This is a design standard. This fitting end cannot be used for plug in union.