Florist stick flower cuts in them chuck. Roses and such then put them in the box. They hold water while the flowers get transported.
Most florist will sell them to you for like 15 cents a piece. They work best by stiking the clone stem through the hole in the lid and then wrap the stem with some wet paper towle so it fits down in the plastic tube and then snap the lid on. No drips that way and they stay wet. Otherwise in the mail even in a plastic bag the water will mostly leak out of the tube and the clone might dry.
i have seen these a million times, never thought of using them for anything beneficial to my interests, but they are perfect for long distance relationships.