A debranching stent graft limb and methods for its use, where the limb comprises, a main body stent graft limb with a bifurcation defining a first and second leg, the main body stent graft limb has a distal end and a proximal end, the main body stent graft limb has a diameter at the proximal end in the range from about 14-18 mm, the first leg has a diameter ranging from about 8-12 mm, the second leg has a diameter ranging from about 6-10 mm, and the distance from the proximal end of the main body to the distal end of the first leg and the second leg is in the range from about 70-90 mm, and the diameter of the first leg is about 2 mm greater than the diameter of the second leg.