These were a lot stronger than I thought they would be. I used them to make my son's flashcards, and I have even put spare keys on them. I won't leave them on there too long, just in case, but they don't just pop open and they come in multi-colors- ( gold, pink, turquoise, green, blue-ish, red, purple) which for some purposes is a great thing. Size wise the diameter is a little larger than a quarter, not much, but a little. For those of us who need something to compare to size wise. I'm one of those 'need to know' kinds of reviewers.I still have tons left and find lots of uses for them that you'd never really think you'd use them for. Example....... a button fell off a pair of shorts, so I used the ring to go thru the button hole and the belt loop. Took a couple rings, but then just wore shirt un-tucked. Embarrassing, but sometimes you gotta work with what you have. No, I couldn't find a safety pin. :)I would recommend these for every college student out there, and actually any student or mom of younger students of any age. For flash cards or to hole punch a card or paper art that covers my fridge and use the ring to hang it up. You can be creative and find lots of uses.I purchased them for flash card purposes and they've been used a lot. Great thing to have on hand! You could even link them together like the old construction paper Christmas garland. I'm not going to, but just another example of the many uses that came from the Book Ring. I'd buy them again if needed. And this inch and a half works well for flash cards. Smaller , the cards may not move very easily. Thanks!