I believe they last for months if not years, based on what I have read. They are even lower tension than the flats at about 122 pounds per set vs 135 pounds, from memory. I have a set but my only issue is they need space to vibrate, being looser, and so the action has to be cranked up a bit (and the truss rod loosened). SO there is a bit of a trade-off between ultra low tension and higher action in my view