Nyogel 760G (50g)

Nyogel is a lubricant for use on rubber-type items, like O-rings, gaskets and such. If one of your lights shipped with really dry O-rings, too much friction can destroy those seals. For example, the O-ring on the tailcap of my HuntLight FT-01XSE Cree P4 was so dry that it was really hard to remove and replace the tailcap, and the O-ring was starting to shred. After applying a thin layer of this most excellent goop, the tailcap was nice and smooth, and probably more water-resistant as well.

50g is a lot of Nyogel. To give you an idea of the scale of the above image, this tube is longer than an incan MiniMag! I got it at LightHound for $15, and it'll probably last me a really, really long time.