The ST-20 silicone membrane is the original part of your Crown CWL-309 joysticks.
It allows to give a better reactivity / repositioning to a joystick used intensely for several months.
The ST-25 silicone membrane is the original part of your Crown CWL-309 joysticks.
It allows to give a better reactivity / repositioning to a joystick used intensely for several months.
The ST-30 silicone membrane is the original part of your Crown CWL-309 joysticks.
It allows to give a better reactivity / repositioning to a joystick used intensely for several months.