This is a Pitbull Tactical Magazine Pouch known as the Universal Mag Carrier, model UMC02BLK.
The last mag carrier you'll ever need. The Universal Mag Carrier Gen 2 allows the user to comfortably conceal any pistol magazine from a 9mm single stack to a 45acp double stack. Inside the waistband or outside the waistband on any 1.5" belt. By default the Universal Mag Carrier Gen 2 is only as deep as a single stack 9mm. As a magazine is inserted the Universal Mag carrier dynamically adjusts in size. The flared opening and rigid design allows any size mag to be inserted with ease perfect for gearing up for the day or admin reloads.
Features:
Fits any pistol magazine from a single stack 9mm to a .45 double stack while maintaining a low profile
No screws or adjustments necessary. Ready to go out of the box.
When you draw a magazine from the Universal Mag Carrier Gen 2 it decreases back to its thinnest profile, keeping out of the way when not in use.