From the manufacturer:
The latest addition to the Gelly Roll® line, Moonlight 06® & Moonlight 10® Pens are our most exciting. Now, the brightest and most vivid Moonlight colors are available in fine point to create eye-catching details. Gelly Roll Moonlight works like a paint pen on colored papers, vellum and photographs. The fine line allows for the ink to dry with very little wait time, minimizing the risk of smearing.
The creamy, smooth, opaque ink is perfect for writing in journals, decorating cards, pattern drawing, or detailed accents. All colors are bright on white paper and produce outstanding effects on quality black paper. The fluorescents even glow under a black light source, popping the colors right off the paper. Create fine lines on any artwork and leave a colorful mark thats uniquely your own.