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.