Filters 16.5 stop ND filter

I see this is a really old thread (it just popped up on mine), but what an intriguing filter! Seems like it's a unitasker -- for shooting photos of the sun. :)

Obviously GAS, but I'm curious what else it could be used for :)
Somewhat interesting, stumbled over this again, and recalled that I actually have a 15 stop filter that came along with a Lee filter set I bought some years ago. Never used it, though.