You can connect your USB-A cable to a separate USB-A charger to charge your smartphone or another device. More and more chargers have an oval USB-C port. Your old square USB-A cable won't fit in these chargers. Choose a separate USB-A charger if you still have a lost of USB-A to Lightning cables to charge your Apple devices. Keep in mind that nowadays, most new smartphones, including iPhones and Samsung devices, come with a USB-C cable. Be sure to check which cable is included with your new device before you buy a separate charger. Most other devices, like headphones, e-readers, and smartwatches, still come with a USB-A cable.