Well I don't know what's wrong. I suspect the threads on the extender are out of spec or something. It arrived today and I tried to screw it in but only screws in a bit. I tried some CLP to see if it would work and nothing. No matter what I try it wont screw in any further. In fact it got "stuck" so I had to use vise grips to remove it. The tailcap screws in all the way on the flashlight so I don't think it's the tailcap. Yeah also the extender is gray and the flashlight OD