They take you for a simp 
No offense to whom you have asked it’s nice to reply but for say bullshit “take 20 day to assembly” I cry with laughter.
2 cells in serie light or not the more common, I don’t have idea for substitute
Check this thread for a good idea of various light in Banggood
Convoy L6 XHP70.2 for trhow and flood L6 gt and L7 for throw
Astrolux FT02S for similar LED configuration single 21700/26650 light (warning this light is the queen of black donut ring, you have the hotspot, a black donut ring and the spill with 1 other black donut in the middle)
You need better define what is “tactical” for you, size, button on head/tailcap.
So check my link and define better for anyone give idea