Dustless Fluorescent Chalk 6pcs, 6 Colors

This chalk is softer and it's not as prone to breaking. The "dustless" argument is hogwash.It's a bit nicer than cheap chalk ... but it's crazy pricey. I'd rather use chalk markers which actually are dustless. With the state of technology these days, projectors and smartboards have taken the place of chalk based presentations. The chalkboards have content that are much more static.

I mostly use these with a 405nm LED to fluoresce. 405nm is not technically UV (it's "near" UV) but safer to use than true UV. That said... I have tested it with 365nm UV (which is UV-A) and the blue & violet still don't have a strong fluorescing effect.This isn't so much a ding on the product. It's normal for blue & violet to be difficult to show the effect because it requires higher-energy wavelengths.All the other colors work great!

broken chalk

Updated 12-17-16 -- Even though they were smaller than expected, they last a very long time. I only ordered more because I am giving them as a gift. My first pack will last at least one more Halloween even with decorating a side walk about 100'x5'. Definitely worth The price and they arrived earlier than expected, againThe image makes these look much larger and even though I saw reviews about the chalk size being smaller than expected I was still a little taken back by how mall they are. They are also CRAZY dusty the ground on the walls were drew was absolutely covered with chalk dust. As for color and glow under a black light they get 10 STARS!!! The color made all the difference when I saw it at night.

The glow well under blacklight. Writing on concrete I've found them to wear down quickly and I've snapped a couple in half after writing only a few words so far (see photo).

This chalk is great and looks awesome in daylight and black light. The photo was taken under UV light, but it does no justice to how colorful it looks (thanks to phone UV filter).Not sure why it's called dustless, it makes the same mess as any other chalk.

Smaller than I thought they were going to be and one was broken but they’ll serve there purpose for a black light party! They’re barely bigger than chapstick in comparison.

Seriously...here's what she did: "Mwa?! Yellow - I love yellow! Let's use yellow for the particle. And - OOOH! - look at this ORANGE! We will use that for verbs! And purple for adjectives!" Yes, it was truly Christmas in March for my Korean Language professor. These colors are bright and beautiful, with virtually no dust transfer. Great purchase, I will buy her more as a thank you at the end of the semester.