The standard magazine is a 10-round magazine. The 10-round magazine makes this a good option for states that have a 10-round magazine capacity limit. States like California, Connecticut, Hawaii, Maryland, Massachusetts, New York and New Jersey all have implemented 10 round capacity-based magazine bans. The extended magazine gives this pistol 13-rounds of 9mm ammo. This puts the S&W M&P Shield Plus on the same level as the SIG P365 and the new Ruger MAX-9. The new Ruger MAX-9 holds 12+1 and I believe the SIG P365 offers an optional 12 and 15 round extended magazine.
13+1 Extended Magazine Amazing
FLAT FACE TRIGGER
Found across all M&P Shield® Plus models, the flat face trigger will give users a consistent trigger finger placement allowing for more accurate and repeatable shooting
ENHANCED GRIP TEXTURE
Based off consumer feedback around the M2.0™ grip texture, Smith and Wesson implemented a more balanced texture. The stippling allows the user to manage recoil, keep a firm grip, and not irritate the skin while carrying concealed.