The following is from the S&W site.
M&P(R)9 SHIELD™ | Smith & Wesson

"The reality of protection is that you never know when you’ll need it. We took the power and features of our full sized M&P pistols and put them into a slim, lightweight pistol the size of your hand. The M&P Shield is an easy to conceal pistol that offers professional grade features with simple operation and reliable performance day or night. One million Shield owners can’t be wrong."