With the SAVE-BIRDIE foam roundel you can keep the shuttlecocks cool and moisturized. The foam roundel can contain 2.5 cl of fluid without leaking. Moreover, they are antimicrobial which means that you can easily use ordinary tap water. In the longer term, it can be necessary to add a little Rodalon or a similar product to the water. Just fill the foam with water and shake off excess water.
With 5 roundels, you have good options for wiping the shuttlecocks while they are in the cardboard tube. Just be aware of the fact that the foam dries out relatively quickly in a cardboard tube.