Losing your light when night hunting can be extremely frustrating, if not damn right dangerous, that’s why every precaution must be taken to keep it in working order, and this includes waterproofing.
This is especially true if you also use this to navigate, which often is the case although pairing a handheld white lamp with a colored rifle mounted one is not uncommon.
Waterproofing is done by adding rubber O-rings to the connected areas of the casing and sealing the gaskets, like plastic or metal, even if finely polished can generally allow for small spaces, such as scratches through which water could sip.