Sliders are used with magnetic hall sensors
The problem with those is that they have a very high parasitic drain
So if you forget to turn off the light it will depleet the battery
I think there was a Jetbeam light which had a rotary brightness adjust with magnetic sensors, additional when the rotary was turned in the off position a small switch was pressed and the power to the magnetic sensors and driver interrupted
There are Imalent lights that use a rotary adjustment in the Tailcaps using a potentiometer which is seaked for water tighteness
One of their lights I have reviewed here
