RCCC stands for Red Clear Clear. Such an RCCC filter consists of four filters: one red and three clear. It is constructed like a Bayer filter, with clear filters in place of the green and blue filters. This application is not about proper color reproduction, but only about increasing light intensity.
In the RCCC filter, one filter element is red, and the other filter elements for blue and green are clear, so that the incident light can pass through to the image sensor. The clear filter discs have a monochromatic character.