TamBee 100 Pack Disposable Tea Filter Bags Tea infusers 4" x 6" Empty Cotton Muslin Drawstring Seal Filter Tea Bags Drawstring Herb Loose Tea bag（4" x 6" /10 x 15cm）

It's a synthetic fiber, not cotton or muslin. I don't know how they've gotten away with this sort of advertising.

Purchased these to use for “dry hopping” home brew (with various additions). Felt good about it after first use (alcohol sterilized bag and spice), however the second time I went to use one, I placed one in the oven with some cinnamon and nutmeg to bring out some flavours and sterilize prior to adding to brew. After a few minutes, the bags had completely melted into a polyester/plastic(y) mess. I will note that the drawstrings were intact, leading me to believe they are the only true cotton component; bags ARE NOT.

Perfect size for hotel coffee makers when you want to bring your own coffee/tea! Easy to fill and to close! Great for travel bags!!

Really helps with keeping the tea container clean. The bags work great as we fill them with our own blend of items to make our tea.

I use these for brewing beer when I need to add different flavours. The flavour seeps thru very well.