The seal is a flat piece of very soft rubber. It is not pressed or glued. If your tire valve is not in the 12:00 position, the seal will fall out. When the valve is in its usable position, the gasket does not seal anything at all. This can be a one-time mistake. What is not disposable is the inside diameter of the fitting. It's so much larger than a Schrader fitting that it's difficult to keep the ignition centered and therefore tight. It really is rubbish. Now I know why the company is charging $39 for the Swiss version and $79 for the US version. You probably work a week or a month.