Nicodemus,
Are you saying that these may be simply "blanks" from a bottle factory with a cool cap added?

I have two that I got at Outdoor Retailer; one is longer while the other has a slightly wider neck below the screw threads. The wider neck does not really allow for wider items to fit.
These tubes are kind of cool but as I try to fit different items into them it is apparent that they are limited to containing small and thin items only. Also they are a bit bulky to use as a module IMO.
Regardless I thought they were cool when I first saw them at OR; they were giving them away like hotcakes.