Originally Posted by waktasz
I thought the frames were the same. Mine has the hole in the side and the little arrow indicating safety on but no safety. It is a 9Pro
I just looked at my 9 Pro and 9 FS and then the manual.
I think what you are seeing is the plug over the internal lock. Or the place for the key if you have an internal lock. Just in front of the rear most roll pin on the left side right?
Look at your manual, the thumb safety sits in cut outs at the top of the frame and is on both sides of the pistol.