An occlusion device for implantation within a body vessel is provided with a screen member and an associated support member. The occlusion device is radially expandable from a compressed condition, suitable for inserting the device in an introducer, to a deployed or expanded condition within a vessel. The screen member includes a plurality of substantially diamond-shaped openings in the compressed and expanded conditions. The porosity of the screen member is less than the porosity of the support member in the expanded condition.