Dykem 11954 UV-Fluorescent Medium Marking Pen - 91195 [PRICE is per EACH]

The media could not be loaded.  this one actually works and it is very permanent. I’ve tried another known brand and it seem kind of hit or miss we always had to press the tip to release more fluid whereas this one is pretty consistent. this one’s a little easier to write with compared to another well-known brand which tends to bleed out more of the edges of your letters, however both brands including this one are just too large of a tip, it would be difficult to write anything unless you’re littering is greater than half inch. Why neither one makes a smaller tip is beyond me.The pics and video are about 6mo old and located in the middle of the floor where I accidentally shook a little too hard with the cap off, As you can see it does hold up.

This pen did make very nice bright blue UV marks on a painted surface that we needed to mark. There are a few difficulties though. First, it is hard to get the right amount of marker fluid onto the marker tip. You need to push in on the tip to open a spring valve for the fluid to run onto the tip. Sometimes, hardly any fluid comes out. Other times, a lot comes out and drips off the tip and down the wall making marks we did not intend. It is really hard to control the amount of fluid. Second, didn't realize that the marker tip is removable. One time it fell out, again marking an area that was not intended. Had to pick it up and reinsert it back into the pen. Third, marking on indoor latex wall paint dissolved some of the paint onto the tip of the marker pen, which then smears around onto other surfaces being marked. Finally, I don't know if it is the pen dissolving the paint or just the marking fluid itself, but the marks are not fully invisible. This was not bad for our application, but someone else may have a problem with it. All in all, it got the job done, but was much harder to use than a regular marker pen. Wish the fluid would just wick out into the marking tip just like in a normal marker instead of having to keep pressing on the tip to get the valve to open and getting uncontrollable amounts of the marking fluid.

Rather pricey thru Amazon. Unfortunately I dropped it while using it and I don't know if the tip fell off or was pushed inside. I couldn't find the tip and I now have a mostly full pen I can't use. Not their fault I dropped it but still sucks.