Water resistance has been touted as a big new feature in the iPhone 7 Plus—but what actually makes it water resistant? The evidence is everywhere:

Figures 1 and 2: a plastic SIM eject plug with a rubber gasket.

Figure 3: a rubber gasket on the SIM tray.

Rubber gaskets and plugs aren't new technology, but they are effective at keeping liquids and dust out of your phone. But there's a cost—when you replace a component you'll need to make sure you get the gasket in place and that it creates a good seal, which tends to be an extra, finicky step.