A device comprising a single closed loop of elastic filament configurable between (i) a first configuration for movement along a blood vessel; and (ii) a second configuration for lodging within a blood vessel, the second configuration providing a single flow-restricting face sized and configured to cover the mouth of the aneurysm and obstruct blood flow to the aneurysm while permitting substantially normal blood flow through the blood vessel, with the degree of obstruction at the mouth of the aneurysm being such that the aneurysm thromboses when the face is positioned over the aneurysm, the flow-restricting face comprising a plurality of lengths of the closed loop of filament disposed in close proximity to one another in a switchback configuration, and at least one leg for holding the flow-restricting face adjacent the mouth of the aneurysm, the leg configured so as to maintain substantially normal blood flow through the blood vessel.