I've seen plenty of fails on this board from all filter brands. However m1 may or may not source some of their filters from M+H. We don't always know who is making m1 filters in various coo's. That being said I've seen a good chunk of these m1 filters not in the greatest quality that I'd pass unless you run a cartridge filter to easily inspect it. M+h makes different brands and some do better than others. Again, do we know if that south Korean made filter was made by m+h?