I have two habits which make these book weights essential. Both are wind related, either from the ocean breeze while reading outdoors or the ceiling fans that keep air moving indoors. They're light, and narrow enough to be closed inside the pages as a book mark on larger books. This is hard on the binding, so I generally use a ribbon book mark and hang one of these book weights in a handy spot where I'm likely to be reading. The weights in the ends of these are lead, and the underside has the leather rough side out. There are obvious alternative uses, just as with my coin pouch. It's a bit heavier, but rides easily on my belt with $25 in gold dollars inside. Handy for leaving a tip, or for social situations that require a more hands-on approach.