The pebble explorer has a large 8400 mah capacity and dual usb port designed to enable charging of 2 devices at any one time with a 21 a output the pebble explorer is designed to charge tablets in the most efficient way this means that your tablet power is replaced as quickly as possibly when youre low on charge and away from a mains source dont worry if your smartphone is also low on charge because the explorers dual port design means its capable of charging 2 devices at the same time