I use a hogue slip on grip--don't have the model number right now, but I think it was made for a glock.
The rubber slip on fits very tight.........and I trimmed mine at the bottom of the grip where the lanyard hole is. The polymer grip dives in at this point and the rubber slip on did not conform to this shape---so I just trimmed around it.
I love mine ! It adds a slight palm swell to the pistol grip and provides a nice anti-slip grip. That was my major concern with these molded polymer grips, because during the summer months my hands would sweat and my grip would tend to slip.
Not anymore with this rubber grip. It has stayed in place very nicely.
I would urge that everyone give this a try---- mine only cost $12. Do the trimming thing and you will be happy with the fit.
My P-99 Houge grip
JF.