Some of the MK-III's come with these already installed and the last time I looked, you could get these from Ruger, Midway and I'm sure there are others. I installed a set on one of my MK-II's and I like them. My eyes are not as good as they use to be and these work great for me. Good enough that I don't need to go to a RedDot. I retained the origianl rear sight blade which is squared off, as oppose the the V-blade that comes with the fiber optics. .....
Be Safe !!!