A permanent blood clot filter which may be retrieved is provided. The blood clot filter includes a filter section and an alignment section. The filter section includes a filter hub and a set of filter legs whose downstream ends are connected to the filter hub. The filter legs extend axially and radially outwardly from the filter hub to form a conical configuration. The alignment section includes an alignment hub and a set of alignment ribs whose downstream ends are connected to the alignment hub and whose upstream ends are connected to the filter legs. The alignment ribs extend from the alignment hub radially outwardly and then further extend radially inwardly to provide centering of the filter.