Having a dead phone can be catastrophic. You could get horribly lost, or trapped in the rain unable to call a car, or miss a last-minute phone call from the love of your life who’s having doubts just seconds before they marry someone else—and then they don’t get you and go through with the wedding, dooming you both to a life of misery.

So. Get a battery pack for your phone. Even better, get this one that’s so slim, it fits inside your wallet.

The LithiumCard Wallet Battery is only about as thick as a stack of five credit cards, so it fits in your wallet or your back pocket. Its durable aluminum construction keeps it safe during rough trips, and the built-in Lightning connector eliminates the need for a nest of extra cords.

It charges fast (about 1 percent per minute) and there’s also a micro-USB version available for you non-Apple users out there.

Get one now for $20, a 66% discount from its usual $59.99 price—and avoid a life of bitter loneliness.

You can also take an additional 15% off with coupon code: BYESUMMER