I've been using these to pack out my dog's used poo bags for the last three years. The first one wore out quickly, but that was before I learned to be gentle enough to avoid damaging the ziplock at the top. Now, one bag generally lasts several months or even multiple seasons. For what I use them for, they work better than anything else I've tried, including double- or triple-bagging the poo, or putting the used bag in nested Ziplock bags. Maybe an animal can still smell the contents, but they work great for protecting human noses from nasty smells.