AGP Arms mag extension opinion needed

[needmorecowbell]

THR friends, I have been researching adding + capacity mag extensions to my XD9/XD45 mod 2’s. I’m leaning towards getting the ones from AGP Arms that includes the +4/+3 extension with plate and stronger spring for $20. Has anyone used these and are they good to go? Any other suggestions for adding capacity to the 16/13 round full size mags? Thx

 

[needmorecowbell]

Also I would like to know if slide locks back when using them. I bought the Mecgar plus 2 extensions made for Beretta 92s but that fit fine on xd9 mags, but they don’t lock slide back. I’m planning to also get the AGP +20% stronger springs to hopefully fix this