glass run, is an automotive door glass run channel composed of compact ethylene propylene diene monomer (EPDM) rubber. The part is shaped to fit the part of the automotive door frame that comes in contact with the glass window. The glass run serves as a guide when the window goes up and down. It maintains air and water tightness between the glass and frame while also absorbing the vibration of the window while driving or when the door is closed.
[1] Please importantly note that only the relevant portion of the related is displayed above. You may refer to the said customs ruling for the entire ruling explanation.
[1]. https://rulings.cbp.gov/ruling/N021593