The PROMAG SMI 27 is an 8-round magazine for the Smith & Wesson Shield in 9mm. Constructed from heat-treated blued-steel components molded from our proprietary TECHNAPOLYMER and ProMag's anti-fatigue spring so you can keep the magazine loaded and ready for up to six years without concern. ProMag magazines are made in Phoenix Arizona and come with a mfg. lifetime warranty.