I bought these tea bags in the medium size so I could brew loose tea, and also so I could use them as the spice-packet when making stews, etc.
The size is ideal for large-leaf teas, such a chamomile, or coarse spices (such as dried chiles or bay leaves).
Where there is opportunity for improvement is in the closure of the bag. There is a flap integrated in the bag, but contents leak out easily. I've resorted to using an office stapler to seal the flap, and that seems to do the trick. I wish these were available with a drawstring or something, so I wouldn't feel goofy stapling ingredients in the kitchen.
But, overall, they are *very* sturdy bags, and they even withstand hours of simmering in the crock pot when slow cooking meats.