Common NBR Valves Design Mistakes and How Product Teams Can Avoid Them
https://siliconeflowsystems.trexgame.net/how-a-no-drip-valve-supports-hygienic-and-controlled-product-flow
Designing a small part can affect the whole product. A NBR valves 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