Anyone used these? If they function better than a Promag, looks like a good option for carbines.
https://www.etsgroup.us/ETS-30-round-9mm-mag-fits-S-W-M-P-p/sw9-mp-30.htm
https://www.etsgroup.us/ETS-30-round-9mm-mag-fits-S-W-M-P-p/sw9-mp-30.htm