The number of actual lumen output is only 627lm. Not 1000lm, as stated in the product description. It is clearly written in the paper manual that comes with the product. As far as I understand, 1000lm is a max available output of the LED lamp. But due to the internal reflectors and lenses ~30% of light amount is lost on the way from the lamp to the exit of the last lens. Hence only 627lm is emitted for external illumination. I have also compared this flashlight with SIGMA bike light, which is also rated with max. output of 1000lm. And the SIGMA was much brighter (and of course it is more expensive).
quality product and bright.