I bought a new magazine for my Glock 19 and when I got home I noticed something that was different from all my others,it had a cut out for the ambi release that the sf frame models use.The follower is slightly different in the area that engages the slide lock also.When inserted the magazine hangs out the bottom of the grip about 1/8th of an inch.I called Glock in Smyrna and was told that all Glock magazines now have this design so that if they make a SF pistol in that model the magazines will already be able to fit.I reckon that if folks want a magazine that fits right they now have to search for older mags.