Retrievable vena cava filters for the temporary or permanent prevention of Pulmonary embolism (PE) are disclosed. A filter in accordance with the present invention has a tube-within-tube structure with overlapping semi-spheres. The semi-spheres comprise a plurality of expandable legs. The first tube may have a plurality of slots allowing for deployment of a first or second sets of expandable legs on the second tube. The free end of each leg in the first set of expandable legs may be oriented in a direction the same as or opposite to the free end of each leg in the second set. The filter may also be formed from a single tube. In certain embodiments, the filter of the present invention can be retrieved from either end.