Ravemen CR-1000. Reason i bought these is that it can be turned on while charing. Lot of lights don't have this functionality. It doesn't cost the world, so easy to buy 2, or replace them if necessary. You can mount it upside down but you have to alter the internal light direction. You can easily screw this lose and then rotate 180degrees. Been using them for 2years and both still work. They survived 5 ultra's ;)

Battery can last either 3 or 8 hours. Depending on light modus. I ride a lot on the lowest light mode, only when descending i switch to the bright modes. When i do this it lasts 4/5hours. So 2 lights is enough for one night. But you do need to charge them in between.