I have it in my (Korean) epiphone the dot guitar with .10 gauge stings. It's a very high quality product, very well made. It's depth do not exactly fits my guitar neck, I think the neck is 43mm. But that's not a real problem.
It enhances sustain noticeably and it's easy to set it. It will take you some time to set the individual height properly but when you're done with that your setup will be great. I did use a caliper to set it with precision and the result is amazing. Do not set all the strings at the same height. If you want to take the full advantage of the product be thorough and precise. String gauge, neck radius and relief are very important. First set the relief, then the nut height, and then the action for better results. Captain obvious here!
It does change the quality of the sound not only sustain wise (a Lot!) but also tone wise (a little). It can slightly open the high frequencies, not in a bad way. You will hardly notice the tone difference when you play through an amp.
I will definitely buy another one