The title says it all. Inexpensive, tough as all get out, waterproof, watertight, easy to replace the cap. They are test tubes made from un-inflated 2 liter bottles. Here's a link to a site that carries them: http://www.stevespanglerscience.com/product/1367 I got one as a stocking stuffer, and said " I can use these." Figured some people here could as well. I'll post dimensions later.