A collar (10, 110, 210), comprising: - a first end (12, 112, 212) and a second end (16, 116, 216) opposite the first end (12, 112, 212), a longitudinal axis (22, 122) extending from the first end (12, 112, 212) to the second end (16, 116, 216), and a shank (20, 120, 220) extending from the first end (12, 112, 212) to the second end (16, 116, 216) and including an interior surface (25, 125) and an exterior surface, wherein the interior surface (25, 125) of the shank (20, 120, 220) includes a first interior surface (26, 126) extending from the first end (12, 112, 212) to a first interior inflection point (28, 128), a second interior surface (30, 130) extending from the first interior inflection point (28, 128) to a second interior inflection point (32, 132), and a third interior surface extending from the second interior inflection point (32, 132) to the second end (16, 116, 216), wherein the exterior surface of the shank (20, 120, 220) includes a first exterior surface (38, 138) extending from the first end (12, 112, 212) to a first exterior inflection point (40, 140), and a curvilinear exterior surface extending from the first exterior inflection point (40, 140) to a second exterior inflection point, and wherein the curvilinear exterior surface and an imaginary line extending from the first exterior inflection point (40, 140) to the second exterior inflection point form a first area that is sized and shaped to receive forward extrusion of the collar (10, 110, 210) as the collar (10, 110, 210) is being installed, wherein each of the first and third interior surfaces (26, 126, 34) is oriented parallel to the longitudinal axis (22, 122), and the second interior surface (30, 130) is oriented oblique to the longitudinal axis (22, 122), wherein the first interior surface (26, 126) and the first exterior surface (38, 138) form a first zone (42, 142) having a first thickness, and wherein the curvilinear exterior surface and a first area on the interior surface adjacent to the curvilinear exterior surface form a second zone (48, 148) having a second thickness, wherein the second thickness of the second zone (48, 148) is less than the first thickness of the first zone (42, 142). - a first end (12, 112, 212) and a second end (16, 116, 216) opposite the first end (12, 112, 212), a longitudinal axis (22, 122) extending from the first end (12, 112, 212) to the second end (16, 116, 216), and a shank (20, 120, 220) extending from the first end (12, 112, 212) to the second end (16, 116, 216) and including an interior surface (25, 125) and an exterior surface, wherein the interior surface (25, 125) of the shank (20, 120, 220) includes a first interior surface (26, 126) extending from the first end (12, 112, 212) to a first interior inflection point (28, 128), a second interior surface (30, 130) extending from the first interior inflection point (28, 128) to a second interior inflection point (32, 132), and a third interior surface extending from the second interior inflection point (32, 132) to the second end (16, 116, 216), wherein the exterior surface of the shank (20, 120, 220) includes a first exterior surface (38, 138) extending from the first end (12, 112, 212) to a first exterior inflection point (40, 140), and a curvilinear exterior surface extending from the first exterior inflection point (40, 140) to a second exterior inflection point, and wherein the curvilinear exterior surface and an imaginary line extending from the first exterior inflection point (40, 140) to the second exterior inflection point form a first area that is sized and shaped to receive forward extrusion of the collar (10, 110, 210) as the collar (10, 110, 210) is being installed, wherein each of the first and third interior surfaces (26, 126, 34) is oriented parallel to the longitudinal axis (22, 122), and the second interior surface (30, 130) is oriented oblique to the longitudinal axis (22, 122), wherein the first interior surface (26, 126) and the first exterior surface (38, 138) form a first zone (42, 142) having a first thickness, and wherein the curvilinear exterior surface and a first area on the interior surface adjacent to the curvilinear exterior surface form a second zone (48, 148) having a second thickness, wherein the second thickness of the second zone (48, 148) is less than the first thickness of the first zone (42, 142).