I think I found these on zulily, or maybe it was at Tuesday Morning. Either way, I am quite fond of them. The tubes are made of sturdy plastic with screw on tops/bottoms. One lid has holes punched into it so that these make for pretty nifty scent tubes, albeit large tubes. The tubes measure about 15", I think, mayne 13". They are large enough so that the children can only hold one in each hand at a time. I like to add items from my own garden to them so we can begin a discussion of what is in your garden or yard. Our community is designated rural with many of the children very familair with gardening and growing. If I had children in my room with different home environments, the discussion would be different. Here in the tubes we have basil, rosemary, oregano, and lavender.