A portable car jump starter is one of those things that you don't think you need until you really, really need it. This one from Anker can jump start most gas-powered cars up to 6L, and diesel engines up to 4L, and also includes a flashlight and USB ports for your phone to use in a pinch.
It's down to an all-time low $66 today from the usual $100, and with any luck, you'll never need to use it. But chances are, there will come a day where you'll be really glad you bought it.
Anker Roav Jump Starter Pro | $66 | Normally $100