Sounds a little far fetched right? Well they do exist, or at least one is currently available. Since I am a proponent of peeps I had to have one. Ordered it from an outfit called "One Ragged Hole" and replaced a red dot scope on my Markll with it. This thing is neet. Simply replaces the rear sight blade in the factory adjustable sight. The pistol will once again fit in my belt holster. Like all peeps I no longer have to concentrate on the rear sight, just the front sight and the target. Can't wait to try er out.