ProMag SMI31 S&W M&P Shield 40 S&W 9rd Black Oxide Extended

The ProMag SMI31 is a 9-round magazine purpose-built for the Smith & Wesson M&P Shield chambered in .40 S&W. Designed as a replacement or spare, this magazine provides extra capacity over the factory flush-fit options, giving you more time between reloads while keeping a compact, carry-friendly profile at the baseplate.

The magazine body is constructed from heat-treated blued steel and finished in black oxide for corrosion resistance and long service life. ProMag pairs the steel body with a precision-engineered anti-fatigue follower spring and molded TECHNAPOLYMER components to keep feeding smooth and consistent round after round. Engineered specifically for the M&P Shield .40 S&W, this magazine is not compatible with the Shield 9mm, Shield Plus, or full-size M&P pistols.

Whether you are topping off your everyday carry rotation or stocking spares for the range, the SMI31 delivers reliable performance at an accessible price point. Made in the USA to ProMag's quality standards.