Smartphone borescope - GIF

[sossol]

I have two of these. One is wired only, the other can use Bluetooth. I don't use them often, but they are indispensable when I do. Looking into engine cylinders, intake and exhaust in situ is really cool. I have an older iphone that I use for this so I don't risk my good one.
Maybe I'm just not cool enough, but I've never considered cramming one into any body cavity.

Neil