The "Pass of the Iron Cross" only just cracks the 2,000 metre mark - yet it is one of the toughest of the French passes: Around 1,600 metres of elevation gain on both ramps from the south and north-east, spiced up with a few unpleasant surprises.
You can find all the information about the north-east and south ramps in the PDF download.
Downloads:
PDF: France: Col de la Croix de Fer