IDenti-Pens Black & Assorted Colors
These dual point multi-purpose markers have a permanent mark on most non-porous surfaces. One end is for details, with an extra fine plastic point that won't break down. The opposite end is for broader lines, with a tough fiber point built in for heavy use. The ink is resistant to water. Alcohol based cleaners will remove ink from non-porous surfaces.
* Convenient 4pak includes 1 red, 1 black, 1 blue and 1 green pen.