I purchased a set of Big Dot Night Sights from XS for my Shield, including shipping $98.
Tools and instruction come with the sights; however, I elected to pay Impact Guns in Ogden Utah $30 to install while I waited.
I am very pleased with the sights and the accuracy at 7 yards is verified with attached targets.
I shot low until I realized I needed to see the entire front sight over the rear blade.
If you can make a lollipop (see the entire front sight) and the rear vertical line touches the center of the candy the bullet at 7 yards will strike within the candy mass.
You will give up accuracy for the 15 - 25 yard shots due to the big front sight covering a large portion of the 8 1/2" x 11" paper target but for defensive distances (less than 10 yards) the sight is lightning fast and accurate.