I bought one because I wanted the red LED to use in a marker light. Interestingly, it was cheaper to buy this than it was to get a red LED from **** Smith's Electronics. I was going to crack the top off and drop it in to a translucent film canistor with the can lid sprayed with a chrome paint as a start, with some further mods for the battery pack later on. But it got lost in my junk box because around that time, I also got hold of my Krill lights.
In its "as sold" form, it is rather sad and quite pointless. The cells can usually be found anywhere they stock cells for scientific calculators. In my case, a couple of local chemists.