These are steel 30rd magazines from England by Royal Ordinance and work flawlessly in the AR15. These things look and work great!
I took a couple out this last weekend and tested them in my Armalite and a RRA rifle without any problems at all. I also tested them with the USGI Stripper Clips and Guides. The stripper clip guide fit a bit loose, but the stripper clips loaded the ammo just fine.
I snapped some pictures for comparison below. As you can guess, the USGI magazine in on the right. The British magazine has a small rectangular sticker that says "England", other than that, there are no markings.
I'M SOLD OUT OF THESE MAGAZINES NOW. THANKS TO ALL FOR THE BUSINESS!!