Great stuff! Yellow is spectacularly bright, with green close behind. The red is okay (it's not that "safety orange" fluorescent stuff that lights the room up bright orange when you shine blacklight on it - sadly). The blue is the least bright. I got it to wrap wires on key pieces of electronics light adapters and programming cables, which otherwise get lost in the sea of small circuit boards and wires that cover every surface of my room. I just have to cut the light and shine my UV flashlight around, and everything wrapped in this glows like a beacon! Works reasonably well for this.