Embodiments of the present invention provide medical devices and methods for treating a target site within the body, such as for treating vascular abnormalities. For example, one embodiment provides a stent graft including an occlusive material having a preset, overlapping configuration comprising at least three inverted overlapping layers that are folded over one another. The at least three inverted overlapping layers are configured to be separated and disposed within a catheter in a non-overlapping configuration and return to the preset, overlapping configuration when deployed from the catheter.