I have to say, I also LOVE that they glow in the dark. This is mostly because they glow brighter the more time they spend in direct sunlight, which for me directly correlates with training volume. Some nights I get into bed and they are glowing bright, a satisfying feeling that I did work that day. Other times it is barely visible against the darkness, encouraging me to get back after it the next day.
This item ships in sets of 2. Since it is for a challenge, I recommend you find someone else who would benefit from it and give them the other, passing along the #CrushItZone challenge.
It is made out of rubber, please keep that in mind if you are allergic.