Ravemen CR1000. You can find it on Amazon.

The light has a shaped (i.e., cutoff) beam -- so to use it mounted upside-down, you loosen the locking around the fresnel lens, then rotate the lens 180 degrees, and retighten; that will put the light in front of you, and not in the eyes of oncoming drivers. It's plenty bright, and the battery life is waaay longer than claimed. I can't recommend this light more highly.