This is a Raven Concealment Systems Magazine Pouch known as the Copia, model DS94UDMCBKMD-150.
The Copia magazine carriers are premium" duty-grade" injection-molded magazine carriers designed for hard-use" daily concealed carry. Their innovative cavity design and retention system allows them to be used ambidextrously with the double-stack magazines of nearly 100 different handgun models chambered in 9/40/357.
Double magazine carrier
Fits double stack magazines chambered in 9/40/357