ISO 19632:2015 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 35 000 kPa (5 080 psi), diameter 6,35 mm ≤ D ≤ 31,75 mm (1/4 inch ≤ D ≤ 1 1/4 inch) for aerospace applications.

This is a design standard.