hehe. you havent read any E09 reviews, have ya? ;)
It is a twisty light with a simple construction (tightened: closed circuit; loosened: opened circuit) and therefore does *not* have any parasitic drain.
In summary, the E09 is a VERY small keychain light, beautifully crafted and an instant pleaser to whomever opens the tin box (pink, gungray, black). Dont be shy. Buy it. (shill shill hehe).
What it does have is low frequency PWM (as to be expected in cheap lights!) and a not-premium shaped perfect round hotspot like the LD01 formed by the deep Fenix reflector. But imo these 2 weak points are really acceptable given the other strong points of the inexpensive product. Also check out the helpful comparison table which i had prepared!!