This invention is a graft component (40, 41) for use in an endovascular graft system used to repair aneurysms (A) in arteries which bifurcate, such as the aorta which bifurcates at the aortic iliac junction. The graft component (40, 41) includes a means (25, 35) for allowing in situ adjustment of the graft component to accommodate the different sizes required for different patients.