Muji A4 size mesh bag-in-bag with multiple pockets. New ones cost around 1200 yen. I tried using it, but it didn't quite fit the size of my usual bag, so I'm selling it while it's still in good condition. It has been used, so please consider purchasing if you don't mind it being used. I will fold it and put it directly into an envelope, and ship it via anonymous Nekopos.