edding8280 Securitas UV Marker - Colourless - 1 Pen - Bullet Tip 1.5-3 mm - Black Light Marker - for Hidden Marking of Almost All Materials - Invisible Writing, Secret Pen, Geocaching

I sometimes sell stuff I've owned but don't need anymore on eBay. Pretty much everyone I've sold to has been fine but there are a few people who have not. I now mark anything I sell using this pen. It dries well and when I've used it has not been too obvious under natural light. It's best to mark objects in unobtrusive places for security and aesthetic reasons.

Easy to discretely mark plastics.

This UV pen is useful. The invisible ink works well, and UV light reveals the writing clearly in most conditions. It’s fun for secret messages and also handy for marking valuables discreetly.The only reason I’m giving four stars instead of five is that the ink isn’t as bright as I expected under UV light. It’s still visible, but a slightly stronger glow would make it even better.Overall, it’s a good product that does what it promises, and I’d recommend it for anyone looking for a fun and practical UV pen!

UV pen, no prep work required, dries almost instantly and all these months later, STILL going strong.Easy to use, relatively cheap to buy, and functions as you’d expect:Does NOT include a UV light, so I purchased a seperate small UV torch to do the job.

This is a great product for security but make sure the surface is none porous or it eventually soaks in,I have marked a few things now and it works great,I had a small doubt as the pen was a bit squashed and contacted the supplier via amazon and they immediately contacted me with reassurances that it would be fine and as a goodwill gesture even gave me a discount,I highly recommend this especially if you have valuable items

works well for everything i tried except cant write on back of moto g6 smartphone or tab 4 plus 10.1" tablet b/c of coating/finish on them. these are valuable items and important for me to mark. the ink forms illegible beads. dont know if scuffing surface of plastic using scuffing pads on said devices will help . will try. the ink forms beads that make the writing illegible. does anyone know of alternative uv marker that will work? ty.

Great way to mark personal belongings , especially now when all children seem to have the same bikes / scooters etc. dries very quickly , makes identifying your items nice and easy- just need a uv torch/light.

Only used a couple of times but it works ok, not sure how long they last without being used though.