My surgeon who is #2 in the country, says that "today" OnX is the "only" mech valve he would implant DUE to its Design Improvements and the fact that leaves open at 90 degrees, not like the others, and that 90 degrees, is one of the most important facts about it. "For me" at 62 made no sense going through an OPS and PLAN for another one at 75+, makes no sense "for me", IF i was 70+ at the time, sure, tissue no pills, but not at 62-63 range; But We ALL have DIFFERENT perspectives, and there is no rigtht or wrong, BUT when it comes to mechanical valves, TECHNOLOGY is always improving, remember those IBM XT PCs running PC-DOS?.... same thing applies..., "in my perspecitve", we all have different opinions, since we do not live in Totalitariam Racist Communist China with Concentration camps..... , good thing OnX it not made in Com China