Why Prototype Testing Is Important for Custom Silicone Valve Seal
https://siliconeopticnotes.trexgame.net/how-to-compare-oil-resistant-rubber-valve-options-for-fluid-systems
Designing a small part can affect the whole product. A silicone valve seal may look simple, but it has a real job to do. It must work with the cap, case, fluid, air path, or light path around it