A seal assembly that seals opening in the wall of a blood vessel has a first sealing element for placing inside the lumen of the blood vessel and to engage the interior wall surface, a shaft integrally formed with the first sealing element and fixed in a predetermined configuration relative to the first sealing element, an outer floating element slidingly movable along the shaft； and a second sealing element, the second sealing element slidingly movable relative to the first sealing element along the shaft to engage the outer floating element and position the outer floating element against the exterior surface and the first sealing element against the interior surface of the blood vessel to seal the opening in the blood vessel.
