They and a couple others with the same basic principle have been around for some time. If you think about it... it's a stupid idea. Instead of having your two sight plains 28-32 inches apart... they move them up so they're only 10 inches apart or less. ANy error in aiming WILL be exaggerated and magnified down range. If this principle had a hills worth of beans to it's merit... we'd move our front rifle sights back about 2 feet..[&:][:'(]