I wish there had been a size chart with the description! I purchased both the small and medium, because I was uncertain on sizing. The small fits me, ring size 4.5, and is big on my 8 year old, but she can wear it on a middle finger. They're definitely not children friendly sizes. The medium is big on me, but will work on a bigger finger. I like how they glow, and they're easy to read. However, they also felt unfinished. I actually had to trim little lumps of excess material off the edges. For the price, they work. They're better than the adjustable metal ones that turn your skin green, but were a bit disappointing