If they give a definitive answer then they will be held to that legally. I sharpen knives and people always ask me "how long will these stay sharp?" the answer is the same, depends on the steel, how you use them, how much you use them, how/if they're abused, etc etc... If I say "6 months" then they go home and saw on chicken bones with them, they get upset that they're dull again before 6 months. In other words, treat it properly, don't abuse it, and it should last a lifetime. Anything beside that and your mileage may vary.