We asked Harley, a Proton privacy expert on our team, to walk through the physical gadgets she and her colleagues use to protect themselves when a password alone isn’t enough. Privacy screen protectors: blocking the oldest attack there isA privacy screen protector(new window) uses thousands of microscopic vertical filters, small enough to be invisible, that let light through straight on and block it from the side. USB data blockers: charging without the data riskPublic USB ports carry both power and data, which is exactly the problem when your battery is at 2% in an airport. A USB data blocker(new window), sometimes called a USB condom, physically blocks the data pins while letting power through. Cash: the original privacy toolEvery card payment leaves a record of where you were, when, and how much you spent.