Just based totally on a guess, they say "500" on the side and from the very blurry photo of the front I'm guessing those are Cree XM-L or XM-L2 LEDs so if that 500 is lumens which is a reasonable level for these LEDs considering it's a alkaline powered light that would mean about 4-5w not including driver losses. But those are just guesses and you can drive those LEDs much harder, like 15-20W if you are doing some serious hot rodding, but those lights are not and you can't get that much from alkaline batteries and that 500 may be optimistic. Honestly I would just get a separate bike light that can put out some actual light, lighting is safety equipment and the last thing you want is to be going potentially quite fast and not being able to see very well.