I honestly couldn't tell you. I bought them used and don't know how they were treated (tracked?). The claim was 16k but if it's 16k of track only then I would expect an excelerated failure rate. I can't attest to the exact mileage claimed but for the money I have invested so far, I'll have no problem paying for the rebuild!
Unfortunately the set I have were not customer serviceable and required machining to retrofit a schrader valve. I'm not saying it can't be done but this isn't as simple as changing a few o-rings and recharging on the first go around. Mine had more problems than a simple leak and had internal damage not allowing it to be adjusted with the knob. My right front wasnt dampening anything!
Honestly it went very smoothly and would recommend using them.