A Rubin valve, often referred to as a "Rubin-type valve," is a one-way valve used in medical devices, particularly in respiratory and ventilatory equipment. These valves are designed to control the direction of airflow or gas flow in a unidirectional manner. While you mentioned a "Rubin valve plastic," the primary material used in Rubin valves is typically silicone rubber rather than plastic. However, the term "Rubin valve plastic" might refer to a specific model or variation that includes plastic components in its design.