I hate all the slip on grips. I don't like palm swells or finger grooves. Pachmeyer makes one with neither of these, but it is for larger guns. And, the rubber is super thick.
Go buy a cheap 16" bicycle innertube at Wal-Mart. I have used this for years now, on many guns. I am finally near the end of that 1st inner tube. If you cut it too short or two long - just try again and cut another piece.
After you install - wipe it down in oil and then wipe it off with a rag. This gets that white powder off. Then, you are good to go. It is the thinnest way to have a rubber grip on a polymer gun. Its ugly, but works fantastic!