I think I got the 2.36 x 3:15 size. These might be a bit bigger than the common tea bag, but just big enough to fill - a teaspoon comfortably fits inside, making it pretty easy to bag teas, if you’re patient. I am getting a heck of a lot of use out of these: bagging all of my loose leaf tea to take to work, making little satchels from used tea/cedar/etc for my shoes, gym bag, closets, and other small spaces. I probably already used more than 100, so these 600 bags won’t last me a lifetime.As far as sturdiness, I have only ever ripped one while filling it, it might have been my second or third one ever. So it is definitely an easily avoidable issue, they are sturdy enough to be used as they are meant to.One unexpected property is that the cotton from which the strings are made has a strong wicking property. So if you let it hang all the way down out of the cup it will get wet and potentially even start to drip. Might be useful if you want to water your plants when you’re away - it’s an old school trick. Less useful if you set your cup on some documents.I will be buying more of these when I run out.