Arredondo mag extensions?

[Cybrludite]

Anyone have any experience with these? They add 6 rounds for 9mm, or 5 for .40 S&W/.357 SIG. The thought of 20 shots in my M&P makes me giggle, so long as it'll deliver all 20 reliably.

 

[tactical723]

I have it on my full size M&P 9mm Pro, functions with 23 rds, rock and roll with no problems, pretty well made for the money, does stick out pretty far though