This tool is almost perfect for me (DSAT Gas Blender Instructor incl. Trimix). Very good user interface, does everything it is supposed to. Also usable for Nitrox, several standard EAN mixes are included, or simply enter as custom gas mix that contains no helium. Only four points, because the bleed calculator of Nitrox Tools from the same developer is not yet included, and because it does not support Heliox mixes yet.