Flashlights on collapsable batons are a BAD idea generally.
It makes them longer which means it sticks into as you work.
It does not allow you to do a but cap strike or jab. It shifts the weight/balance way foward making it swing more like a baseball bat than a baton reducing your multiustrke capability and controlability. I did recently see one that was a simple protected led with a small switch that was about the size of a stock cap. I may try that one. I have tried/seen a lot of deferent gadgets for batons over the years. Most batons are better off stock. I am currently or have been Instructor or instructor trainer for ASP,PPCT or Monadock. Whic by the way, they all discourage use of baton
lights.