I used this holder for a double stack Ruger Max 9mm magazine....I am a lefty, and the idea was to hold an additional magazine in my right pant coin pocket. The mag placed inside the holder was a good fit in the pocket, but it only took about a week for the mag holder to stretch out and now it will not snuggly hold the mag. Its so loose after only a week that it is as if the mag holder does not exist. I know this mag holder was for a single stack ...it was too loose for even a single 9mm or .380 cal
I have a couple of Sticky holsters, so I bought a Sticky magazine holder so they wouldn't get lonely. Happy to say all is well now. They get along just fine. I'm a big fan of Sticky.