What motors are they being offered for?

I purchased one for my MK 101 over a year ago.  It had a vibration at about 70% power. They replaced it two more times for free but all of them had the vibration. Each time they said they had done something differeent to solve the problem (they were aware of the vibration) but in the end I gave up on the prop.  At any speed above and below 70% it was quieter, smoother and faster than the MK prop.  The 101 prop was the only one with this problem that I am aware of and they probably solved the issue by now.