Pro mag mag well adapter - Pro Mag AR-15 / M16 9MM Magazine Adapter Block For Colt 9mm SMG Magazines, Quick Change

Got the pro mag adapter for my recent AR9 pistol build. The adapter itself is made of mostly plastic with steel inserts for critical areas such as the feed ramp, ejector and bolt hold open cam. It is a two piece design that inserts from the bottom of the magwell and does not require the bolt release to be removed for installation. It is a quick change design. It also works with standard a bolt catch. The last round bolt hold open feature remains functional when used with colt smg type mags. The mag adapter is a bit tight , mags won’t drop free. I think prolonged use may resolve that. The adapter also fits well with milspec lowers. ( colt, Anderson, bcm, spikes). I can not really attest to the durability of the adapter. Time will tell. But it is a cost effective alternative to other products that cost substantially more.