To me, this seems like a dumb question, but I saw a thread earlier today that mentioned that a G20 Gen4 is a G20SF (I have been unable to find that thread again). There is a chance that what I saw earlier was regarding another Glock model, which would explain why I haven't found it again. Next, I imagine the answer to my thread title question is no. But it would be great if that was a yes. I just traded for a G20SF Gen3, which fits my hand far better than my previous regular G20 Gen3 did. However, I used to also have a G21 Gen4, and one of its smaller/thinner backstraps made it fit my hand even better. I was thinking that possibly I could buy some Gen4 backstraps and, even though my 20SF Gen3 fits my hand really great, maybe I could make it even better.