Here is a white key etched with F8 in Arial, size 8. The laser goes about 0.005" deep. Which doesn't sound like much, but as you can see, you'd have to wear the surface of the keys down significantly to wear the letters out.
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Here is another key. I scraped it with my knife on the "6". So basically, if you don't wear sandpaper tipped gloves when typing, you should be good :smile:
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