I used Efest imr 10440 what should I use nowadays?

LED Flashlights – General Info 1 x AA / 1 x 14500 Flashlights
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Vapcell has a good one: Test/review of Vapcell INR10440 320mAh (Green)

The Efests are still available at a few e-stores. There is a V1 and V2 version.

Both brands offer a flat top and button top, as seen at illumn.