Seal ring

A seal ring, comprising:

• an outer surface and an inner surface;
• and
• side surfaces formed symmetrically about a plane perpendicular to a central axis, the side surfaces connecting the outer surface to the inner surface,
• wherein the outer surface includes:
• a peak portion provided along the plane;
• first tapered surfaces, a diameter of each of the first tapered surfaces being reduced with increased distance from the peak portion, each of the first tapered surfaces forming a first angle with respect to the central axis;
• and
• second tapered surfaces, each of the second tapered surfaces being closer to each of the side surfaces than each of the first tapered surfaces is, a diameter of each of the second tapered surfaces being reduced with increased distance from each of the first tapered surfaces, each of the second tapered surfaces forming a second angle with respect to the central axis, the second angle being larger than the first angle, and
• wherein a width of the inner surface is narrower than a width of the outer surface such that a shortest distance between the side surfaces is smaller at the inner surface than it is at the outer surface.