They work well, I used them to build a spinner for a zoetrope. Sizes may vary slightly, but it's hard to tell if it's my print or a stock. It wasn't something a little threading wouldn't fix anyway, so I keep using it and it's working. Gets a good minute of spin on my project. In the right case, it could probably be more. ALSO SUPER BONUS - The fact that they include a border is amazing. I honestly didn't think they would do that; I thought the picture was for size comparison but no they included a whole spinner which you can adjust if you like. Final comment, they also included a cute little Polaroid map of San Francisco. It was a nice, sweet little gesture that really made the thing more likeable. I will DEFINITELY buy again. THANK YOU SO MUCH!