Many newer cars come complete with USB jacks for charging. But there are plenty of reasons you may want to look for another option: they may be low power, they may be located in a spot that’s less convenient or you may simply need more than the car provides. Here’s what to look for in a phone charger for your car.

Quick Refill

This product identifies your device and safely delivers the fastest possible charge. Anker

USB chargers come in a variety of different amp counts, which tell you how much power is delivered to your device. The higher the amp rate, the more power gets to your phone—and, in turn, the faster your phone will charge. We’ve gone up in amps over time; today, you don’t want to buy any USB charger that delivers less than 2.4 amps per port.

Nearly Invisible

With such a low profile, you’ll barely notice this gadget at all. AINOPE

When shopping for a USB charger, look for one with some kind of lighting—though preferably a subtle one, so it’s not distracting. When driving, especially at night, the interior of the car can be quite dark, and you don’t want to be fumbling around trying to find the charger for your phone. Many chargers have some kind of LED lighting to guide you.

Super Fast

This gadget provides incredibly fast battery refilling to compatible devices and works with both Android and iOS devices. HUSSELL

Beyond the standard amp count, there are a variety of technologies that can recharge devices over USB even faster. The most popular is called Qualcomm Quick Charge; for compatible devices (which include phones from Samsung, LG, and Nokia), this can mean truly outstanding charging speeds. Qualcomm claims its technology can charge a phone by 50% in as little as 15 minutes.