Flexible materials are recommended for the main parts and PLA for the valves.
The holders keep the earplugs attached to the ears, so they can be used also during sleeping. The idea of the valve is to reduce the pressure.
If the 5mm valves don't fit, you can use the 4.5mm. Otherwise, you should scale the 5mm valves from 95% to 97%. All the files are repaired.