The King-Tappan sights were designed by the late survivalist writer, Mel Tappan. Kings Gun Works made them (and probably still do).
The rear sight fit the factory dovetail and featured a white square under the rear notch. The front sight was of the "stake-on" type (not a cross-dovetail) and had a yellow dot. There was a yellow line running across the front sight beneath the dot. The intent was that this line could be lined up with the top of the rear sight and that would give you the proper elevation for 100-yard shooting.
The sights were well-made and worked well enough. Their weaknesses were that the rear sight did not have a set screw to lock it in place. It relied on the the tightness of the slide's dovetail to stay in place. As mentioned previously, the front sight was a "stake-on" and staked on 1911 front sights tend to loosen and come off. One could solver solder the front sight in place, but doing so obliged one to refinish the slide and repaint the front sight's dot and line.
Rosco