These are very handy little filter bags that are designed for loose tea. Once you get to be a real tea addict, you want the full-leaf, loose tea, but you don't want to be eating tea leaves. So you can make your own tea bags! You can make yourself a quick cup of tea at work, and you don't have to keep running to the bathroom to rinse out your tea infuser. Though I do love the Japanese kind of bag that folds up, the Finum ones are biodegradable, and I'm not sure that the Japanese ones are. These are the large size bags, and though at first they seem too large for a single cup of tea, they are big enough to let the tea leaves expand. I have seen them used in two ways in different cafes -- one, they put the bag in the paper cup and hang the long end over the side and then put the lid on to keep the top of the bag in place so you can easily remove the bag when the tea gets strong enough. Two, they put the tea in the bag and tie the top in a knot and just throw it in the cup! So that extra length really is useful for something.