0.7 mm marking pen, set of 3 - UV, Heat makes this disappear!
This is a very cool trick for upper making or as a matter of fact everywhere where you have to make materials. The mark visible by eye, but it really shows a lot better with a simple blacklight (UV). The penmark disappears easily with a little heat, so cleaning the upper doesn’t need any more solvents, rubbing or much effort. Get these and forget the regular silver pens!