I haven't been tested for ADHD but I fidget a lot. I wish I had a chair that worked with the elastic bands, because they look like a lot of fun to stretch and bounce my legs off.
From Core 77:
Those are elastic "chair bands" sold by Amazon retailer Ozio, and they're intended for schoolkids with ADHD, ADD, autism, and/or SPD (Sensory Processing Disorder). Essentially, the child can freely fidget with the bands with their feet during class, which the retailer says helps promote calmness and increases attentiveness.