Thank you! It's an HC3R from HCMags. It holds 25 rounds, like the BX-25, but there's also an attached pocket that holds an extra 20 rounds. Once the mag goes empty, you lock the follower down, pull the spine clip off, slide it over the extra 20 rounds, reinsert the spine clip into the back of the magazine, and release the follower. It's a pretty sick deal. There's a slight trick to getting the rounds to stack correctly, but, beyond that, I love it. A bit on the pricey side, but it came with the rifle, which I bought from a friend who was in a tight spot financially. Roughly, there's about a grand tied up in the rifle, and he gave it to me for $450.
