A filter to be placed in a blood vessel, the filter comprising: a hub disposed along a longitudinal axis; a plurality of anchors branching from the hub, each anchor including a hook that (i) penetrates a wall of the blood vessel when the filter is placed in the blood vessel, (ii) is spaced along the longitudinal axis from the hub, and (iii) is radially spaced from the longitudinal axis a first distance and a plurality of locators branching from the hub, each locator including: a base portion proximate the hub; a first segment that extends from the base portion and along a first axis; a second segment that extends from the first segment and along a second axis, which is distinct from the first axis; and a tip portion that extends generally parallel to the longitudinal axis from the second segment and along a tip axis, which is distinct from the first and second axes, the tip portion (i) engages the wall of the blood vessel when the filter is placed in the blood vessel, (ii) is spaced along the longitudinal axis from the hub, and (iii) is radially spaced from the longitudinal axis a second distance, which is less than the first radial distance; and wherein: the plurality of locators defines a first surface of revolution that defines a volume V1, and the plurality of anchors defines a second surface of revolution that defines a volume V2, and wherein the volume V1 surrounds at least 15% of the volume V2. a hub disposed along a longitudinal axis; a plurality of anchors branching from the hub, each anchor including a hook that (i) penetrates a wall of the blood vessel when the filter is placed in the blood vessel, (ii) is spaced along the longitudinal axis from the hub, and (iii) is radially spaced from the longitudinal axis a first distance and a plurality of locators branching from the hub, each locator including: a base portion proximate the hub; a first segment that extends from the base portion and along a first axis; a second segment that extends from the first segment and along a second axis, which is distinct from the first axis; and a tip portion that extends generally parallel to the longitudinal axis from the second segment and along a tip axis, which is distinct from the first and second axes, the tip portion (i) engages the wall of the blood vessel when the filter is placed in the blood vessel, (ii) is spaced along the longitudinal axis from the hub, and (iii) is radially spaced from the longitudinal axis a second distance, which is less than the first radial distance; and wherein: the plurality of locators defines a first surface of revolution that defines a volume V1, and the plurality of anchors defines a second surface of revolution that defines a volume V2, and a base portion proximate the hub; a first segment that extends from the base portion and along a first axis; a second segment that extends from the first segment and along a second axis, which is distinct from the first axis; and a tip portion that extends generally parallel to the longitudinal axis from the second segment and along a tip axis, which is distinct from the first and second axes, the tip portion (i) engages the wall of the blood vessel when the filter is placed in the blood vessel, (ii) is spaced along the longitudinal axis from the hub, and (iii) is radially spaced from the longitudinal axis a second distance, which is less than the first radial distance; and wherein: the plurality of locators defines a first surface of revolution that defines a volume V1, and the plurality of anchors defines a second surface of revolution that defines a volume V2, and wherein the volume V1 surrounds at least 15% of the volume V2.