The magazine extension and spring work great. You will need a punch to install.. and perhaps a flat screw driver.. Have used them in USPSA matches and they hold up very well..A must have if you compete with an XD...

Fit and finish are exemplary!!!! Work perfect and look good doin it!

Ended up only being a three round extension instead of the advertised 4 additional rounds. Definitely doesn’t look like it was designed to match the XD40 grip but instead is a weird smooth extension that is smaller in diameter than the grip. Fortunately, no issues feeding even with a full mag dump.

I had a few of these extensions and I like them so much that I got more for the rest of my XD mags. They look like the gun was designed to have them on it. Getting 20 rounds in tends to require the help of a good speed loader but it can be done and feeds the first round normally. When assembling or disassembling it, beware that the extra power spring can cause extra power flying parts!

I only got +2 from my 16 round mag, and with the extension the mag release is far more difficult to depress on either side.

Not happy that it's not +4, but I can beef up my thumb squeeze and I'll take the +2

Easy installation. Full mag rattles a little bit not a deal breaker. Haven't had a chance to shoot yet—I've manually racked through a couple of full mags without a problem.

fits great, easy to install, 4 extra rounds !

Spring has a lot of shake when make is full

I don't know they said just +4 but it's +6 on my mag lol with the spring that comes with, just to be clear, and quick shipping too highly recommended

Overall these are pretty good. The only extensions I've found for the XD that actually lock into place. Two of mine worked great, but two had to have the edges filed down significantly just to allow the magazine to seat in the magwell and then also be able to easily be released with the button. Once I finally filed them down sufficiently the work well. The other drawback is that they are extremely difficult to remove once installed. Not impossible, but I have yet to find a single way to do it successfully every time. Also, the springs compacted after the first loading and significantly lost their power. The slide still locks back after the last round, but I'm nervous that any further compaction of the spring will eventually lose the lockback.

Didn't come with instructions but easy enough to figure out how to install. Really solid product. I did need to us a loader to get all 20rd in. I would recommend this to my friends.

I bought three extensions and added them on to one XD9 and two XD40SC magazines. In the .40 however, it will only accept three extra rounds. Nevertheless, I now have a backup 15 round magazine that I can carry in my pocket for my EDC.

I have heard people talk about not using extensions because the plate will pop off the bottom, but AGP is correct when they say this will not happen with their extension. It is on solid (that also means that if you want to take it off, it's a hassle, as I found out, but not impossible. I consider this a positive, however, because it means I can trust the extension to stay on).

One negative about this extension: if you want to use it with the XDSC 12 round mag and the extension (the part that just fits around the mag), you have to trim off the top part of the plastic on the lip of the AGP extension in order to get it to fit. That's not difficult however, as it just takes dragging knife or sandpaper across it a few times.

All in all, a very easy, quick, and cheap way to get a three/four extra rounds loaded up.

I've only run 100rds through my mag with the extension, but not a single problem so far. I'll be using this mag at a 3-gun match later this month and if it continues to perform well I'll DEFINITELY be ordering a couple more. Thanks for a GOOD product. (after I abuse it a little I'll find out if it's a GREAT product)

I bought 5 of these and had zero trouble installing them. The included instructions are more than antiquate. I was also able to load the +4 rounds by hand without the need for a loader. As an added benefit, for folks like myself who have large hands, the extension increased the area for the palm of my off hand. I have nothing bad to say about these extensions. I've put 100 rounds through them already with zero loading issues.

Easy to install. Fast delivery.

Installations wasn't quite as easy as some here. After installing, there was interferance and I had to uninstall, sand down the top edge and re-install. Now it works great and I am extatic to have 3 more rounds in my clip. Capacity is the one downer on the XDs.

The installation was a breeze and functioned exactly as expected. I had read great reviews about the AGP mag extensions on the forums and decided it was time to upgrade all of my mags!

great product. only took seconds to install. only +3 in xd.40