Since I already have two 2400 lumen lamps identical construction, I ordered these 4 3800 lumens bicycle lamps for me and my biker friends. The lamp reaches at level 2 almost the intensity of my 2400 lumen lamp; the performance of the battery is 1/3 shorter than that of my "weaker models". With pleasure I send you by e-mail to the juxtaposition of the two lamps. 20 seconds before the battery is flat, the indicator light on the back red on - unfortunately too late to change the battery if replacement battery is available. Stay away from this product, false lumen indication; prefer 10 euros more to spend on more brightness and longer operating time.