Kokuyo's Mark+ Two-Way is a fantastic double-ended highlighter. There is a traditional chisel-tipped highlighter at one end and a fineliner at the other. Efficiently color code your most important notes with this handy marker.
The five color sets come in either a monocolor palette, or a gray tone palette. The monocolor versions have the same color of highlighter and fine liner, whereas the gray tones have a grayish color on the fineliner side, such as pink highlighter with a pink-gray fineliner.