When I was looking for new mouse feet for my device, I had trouble finding a pack of glass ones that didn't lack the center piece. This kit is one of the few if not the only one that has that. It's also rather durable and fairly smooth. Personally, I noticed a big difference with the replacements as it is quite a bit smoother. Your results will vary depending on the mouse pad you're using. I'm using a really cheap one I bought a while back and can't really complain. As I broke them in, I noticed it became slightly grippier, which is great because initially the mouse did feel like it was sliding a lot more and less forgiving in games. I dropped my old DPI in half and got a lot more movement out of the mouse. It's definitely an upgrade I'll make with any future mice.