Most everyone on E-Bay sells Snap On tools with The Lifetime Guarantee. That is great. But there is a problem. That is if there are no grind marks or any signs of misuse they will take care of it. But if you buy second hand Snappys and there are intials engraved on them DO NOT GRIND THOSE INITIALS OFF. If you do alot of dealers will not honor their warranty because of  damage to the tool itself. I have bought several tools off from E-Bay with the engravings already removed and could not get a replacement because of the defacing, alteration and/or misuse of the tool. They told me if the etching or engraving had not been ground off they would replace it no problem. It has to do with the company policy. So in essence to the topic etchings or engravings (initials) do not effect the performance of the tool, but grinding on them however slight they may be the warranty is voided.