Ambidextrous, IWB/OWB MRD Magazine Holster. Carry your spare mag with you at all times. Extremely versatile with mounting holes on both sides to accommodate your preferred carry position for either IWB/OWB Carry and Right Hand/Left Hand Draw. Mag Holster comes fully assembled for RH IWB Carry, but is easily reconfigurable with just a phillips screwdriver. Our MRD magazine holsters come with a 1.5" Belt Clip.MRD Mags are universal for the caliber and round configuration (single stack vs. double stack). Mag Retention is easily adjustable via the Allen Key on the MRD which puts pressure on the flat side of your mag. Magazine Holster Selection:9MM/40SW Single Stack9MM/.40 Single Stack Magazines (up to 0.65" wide)9MM/40SW Double Stack9MM/.40 Double Stack Magazines (up to 0.86" wide)45ACP Single Stack45ACP Single Stack Magazines (up to 0.55" wide)45ACP Double Stack45ACP Double Stack Magazines (up to 1" wide)