Advise needed for buying a compact and very effienct 300-400 lumen light.

LED Flashlights – General Info 18650 Flashlights
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For maximum runtime, you need
-Buck driver: Linear driver( amc7135, Fet) drivers will burn more energy into heat than buck driver
-Latest Led: xhp70.2 will be more efficiency than xhp70
-Under driven led: a XP-G2 led runs at 400 lumen consumes more energy than xhp70.2 at same lumen

So i suggest you klarus Xt11x, at 400 lumen it can hold for 4 hours