This is a Sticky Holsters Magazine Pouch known as the Mini Mag Pouch, model MMP.
The Mini Mag Pouch is a magazine and accessory holder that can be mounted OWB by using their A Frame design to attach to the belt. You can also keep the A frame closed and carry IWB or in a pocket. This is used for small single stack magazines.
Features:
Ambidextrous
American Made
Latex and allergen free
Multi-Use and Multi-Fit
Part of a modular system