My extensive testing has shown Total Seal rings can produce zero leakdown and can continue to do so for as much as 100,000 miles. Here is how they work: Firstly, the gap for the lower ring is on the opposite side of the bore where it is sealed off by the upper ring. Gas pressure, communicated from the top side of the piston, passes down and through the gap as shown or through the radial gas ports if the piston used has them. This pressurizes the backside of the ring, ensuring firm contact with the cylinder wall. Because both upper and lower rings are virtually in contact with the bore, no leakage route exists.