Peanut you made me chuckle, I saw the containers and thought "oh, he's putting out geocaches" but then I read the post and they're actually match holders. I've seen them hundreds of times but they were always called bison tubes and were uses as caches.
I usually see them in the camping section. Funny, got a buddy who also has german sheppards. He is always losing his house key but is too paranoid for a hide-a-key. I told him to put a key in a match tube, clip it to his dog's collar. No one would take it!!
Know nothing about the geo stuff... but i had thought they'd be handy for leaving clandestine messages, even submerged.