Springfield Armory MAG XDM SLV 3.8 BCKSTRP#1

Highly recommended!
I bought this item to enable use of the larger 9mm magazines in my XDm Elite 9mm Compact, (Bud's Item Number: 129224). The pistol comes with 14 round mags that work great for concealed carry, but I wanted the option of a larger mag as a spare or if I want to use the little pistol as a house gun. I'm happy to report that it works well with the older XDm 19 round mags as well as the XDm Elite full size 20 & 22 round mags! While the larger mags insert and lock in the smaller pistol without the sleeve, XDm models don't have a magazine overtravel stop. What this means is that if you install a long mag and happen to press up on it while firing, (such as using it as a brace), it can cause a mis-feed. These sleeves prevent the mag from going in too far and causing this malfunction. Just remember to pick the sleeve size to match the installed grip module on your pistol. Mine is using the "1" or small backstrap since I have small hands.
P.S. I removed the stock mag well, so I can't speak as to the function if you keep it in place.