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 an occlusion device including an occlusive material having proximal and distal ends and a central axis extending therebetween. The occlusive material has a preset, overlapping configuration including at least three inverted overlapping layers folded over one another, wherein the at least three inverted overlapping layers are aligned with the central axis within about 45 degrees or less and 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.
