Is there an o-ring seal under the front window on this light? I can't quite tell by looking.
Yes, and one of the trickier parts is getting the right seals on the various optics. That is why currently I don't recommend going below bathtub level or so submersion until I can test them in a lake. Although all these early lights will certainly be fine dropping them in a creek or in a heavy storm or whatever. My ultimate goal is 50 feet.
The o-ring seal under that top optic is a seal type I've never tried before in order to make the light as small as possible. The seal is actually created on the sidewall and bottom press-fit seat of the optic instead of the top lip. This also allows the optic to perform better by having a larger topside diameter.
-Fraz