The Lancer +6 Single Base Pad Magazine Extension For Lancer L5AWM Magazines are for Lancer Magazines only. If you have magpul magazines, check out this magazine extension:
https://www.tacticallink.com/Springer-Precision-EZ-Pad-Max-Base-Pad-Magazine-Extension-For-Magpul-Gen3-Pmag-Magazines.html
Thanks for the inquiry.
Tactical Link