Dont waste your money on junk
Garbage dont waste your money on this junk buy a p-mag I got one of these magazines and I only got 16 out of 17 rounds in it and it jammed so bad that I barely was able to unload it by hand very disappointed
Great for malfunction practice only
I bought six of these. All six jammed consistently resulting in failures to feed. The issue is in the design and fit of the follower. The follower is too loose in the mag body allowing the rounds to jam in between. I wrote ETS, they quickly sent me six new replacement followers (ETS customer service was good), and those worked better but still not perfect. Now two of my six magazines still jam. These are unreliable, and cannot be trusted for anything but malfunction drills. They do look cool though.
Waste of Money, get horrible over time
I am a LE Firearms Instructor and competition shooter. I bought several of these magazine to use for IDPA and training. they work fine at first, but the more you use them, maybe say a few hundred rounds, and their performance just goes to scrap. I gto a couple cracks near feed lips, chips that came off the edges of followers, and the follower would stick inside the tube not keeping the top round pushed towards the top. I got tired of messing with them and gave up. These will eventually cause your reliable Glock to give you some malfunction clearance practice. Beware
Failure
Neat concept - poorly executed. I purchased six of these mags to try out for a custom G17.4 build. I immediately noticed the rounds not "stacking" correctly in the mag. This did not allow for 17 rounds. I attempted to load and reload four of the mags to get an idea of the problem and if it was just one defective mag. All of the mags suffered from rounds jamming up inside the body of the mag. Also, out of the four mags, only two dropped free. I did not use the mags in live fire. Returned all six. Avoid these.
9mm mags okay, .40 cal awful
The 9mm extended mags seemed to work with only a couple of hiccups which could work out, time will tell. however, the 15 rd. .40 cal mags would not allow more than one round being fired before they jammed. Once fired, the next round would nose dive looking for the bottom of the magazine. Due to the malfunctions of the .40 cal. mags I cannot trust the 9mm mags for anything but range work until they prove out.