What you mean by Triangular would be a light with a large reflector diameter relative to the tailcap diameter while remaining as short as possible? A single 16340 version of a STL-v2?
The X9 is a single-cell/large reflector design but it's still 18650 and it's still about 20cm long...
I've always lusted for the lumapower but i was thinking more triangle .. this started from taking the body off of the mcu c-88 and attaching the tail directly to the head ...And the fact i like the nitecore sr-3 as a nitestand light because it's rock solid face planted instead of knocking over tall tailstanding 2AA lights like dominos .Same with front and rear door lights I don't like seeing them tumble or tip over so i need about a 40mm wide reflector and one little xre in the center .
Same question does anyone know of any big head single AA or 14500 lights