This is the ProMag Smith & Wesson CSX 9mm 20-round magazine. 

The Smith & Wesson CSX may be compact in size, but that doesn’t mean its capacity has to be! This 20-round magazine from ProMag delivers the additional rounds you want without being too unwieldy. 

Its heat-treated steel construction is topped off with a corrosion-resistant finish, making durability the least of your worries. Inside, you’ll find an injection-molded polymer follower and high-quality steel spring that work together to provide flawless feeding.  

And just in case you’re not used to having this many rounds in your CSX, the side-facing witness holes will help you track how many remain. From home defense to your next range trip, these 20-round aftermarket magazines will do the trick! 

Throw a few of these extended magazines in your cart before you forget!