Sharpie Extreme Permanent Markers (black) are very useful to me in my work administering the ACT and SAT exams

In my personal use, the Extreme Permanent Markers are great for marking clothing and gear

These Extreme Permanent Markers make the signs very clear and can be seen at a distance down the hall or from the parking lot adjacent to the main doors of the testing area

Great Markers!

These Extreme Markers are even better than the regular Sharpie markers

Just make sure the surface is as reasonably clean as you can get it before writing.