I found out about this product on social media and bought it because I wanted to keep thick books open. Pros: It can clip books of a certain thickness well at the center pages (photo 1). It's easier to turn pages compared to X-shaped clips. Cons: When clipping at the center of the book, the gap on the thicker side also appears on the thinner side, making it loose and causing pages to turn (photo 2). It's less effective at handling the difference in thickness between the left and right sides of the book compared to X-shaped clips. Its effectiveness is affected by the thickness and size of the book.