I saw these come up for sale on Rainier, and pre-ordered two of them to try out. I wanted to put down a few initial impressions, then update the thread as I get more rounds through them, and do a bit more testing. I would welcome any other opinions or experiences. Overview: I'm not going to copy text from their own ads, but i'm sure the internets can lead you to their website. It appears they have 17 and 19 round magazines for the 17 and 19, a 33 round mag, as well as a 22 round mag that is USPSA limited legal for length (under 140mm). I opted for the 22 rounders for a few reasons. 1-Without getting into the USPSA rules too much, I like shooting my Glock 19 at matches, and now that I have an appendix holster, I will be shooting limited because of the position of the holster. That's fine and I don't really care, but it does allow me to have longer mags. Instead of buying a glock mag, then a $20-$35 extended basepad, I can get a $20 mag that already lets me load to capacity. 2-with they way my spare mag pouch is angled, I could potentially carry this as a back-up mag with no concealment issues. Having an extra 5 rounds is a good thing. 3-I already have all of the other sizes, so why not. Initial impressions: The plastic feels cheaper than other polymer magazines. Ok, it is true and I don't really care. I don't care what it subjectively feels like, as long as it can perform (phrasing...are we still doing that?). Instead of the rougher feel of the glock polymer shell on the OEM mags, or even the magpul mags, these feel slick. They also have a rib around the basepad they claim to make stripping mags out easier. This extends past the grip of even a 17, so not a real advantage of this one, but makes sense for the 15 and 17 round varieties. I took one to the range and shot about 75 rounds or so through a glock 19, and glock 17, and Matt's Roland special (FB post about that coming). You can fill the mag up to 22 rounds, but seating with a closed slide requires a firm push to engage the catch. I did find that with either 21, and more so with 22 rounds in the mag, it would no longer drop free of the gun. I imagine that there is a slight swelling in the body as the spring is fully compressed. I don't know if that will go away with use and wearing in, but I am going to mic it with and without rounds in it tomorrow and see where it is bulging. I don't every see myself needing to drop a fully-loaded mag, especially in a match, when I see these being used mostly, but who knows. They seem to work, after more rounds and more time I'll have a better idea. Overall I am happy with the purchase so far, and hope to get some good use out of them in the coming year.