I have this flashlight with the following basic parameters:
- 138.96mm in length and 31.67mm circumference, as measured by digital calipers that cost more than the flashlight
- Has a 20 Wh 26650 Li-Ion cell (battery itself is unprotected but the flashlight has protection PCB; I'm guessing it might be safer in the flashlight (off) than in a case)
- Is a bit weighty, but certainly not designed to be used as a physical weapon. The wavy pattern on the business end is not at all sharp; I spun it around on my palm and it didn't even give me abrasions, let alone cut my skin.
The most specific info I've found about TSA travel restrictions for flashlights is (1) they can't look like or be used as a weapon, and (2) they can't be longer than 7". I think this qualifies so far...
Are there any other red flags that would make it very likely for this to be disallowed to fly?