How do you use as headlight
-on forehead under helmet ? -NO, that would be silly as it would cover your eyes.
- over helmet ? (is the strap big enough to fit round a helmet ? doesn't it keep slipping off ?)
YES, use strap to hold on to helmet. there is a rubber pad on the back of the light unit. And yes, strap is big enough. And it will not fall of if cable ties are used to hold the light unit on etc. Or one could do, as I do, which is wrap the strap around the peak of a removeable helmet peak.
The One thing I didn't mention is that the light unit itself swings away from the battery part so the light can be angled anywhere you want. Thus when you fix it to your helmet, the light beam is not pointing upwards, but onto the road.