This portable charger will automatically shut down if a short circuit or overload output occurred while unit is charging. Compatibility with all 5 Volt Input Devices; Ultra reliable A+ Li-Polymer battery with 500+ recharge cycles over the life of the battery. Designed with only 3.8 inches in length and 0.8 inches in width which is compact as a lipstick. Connected to mobile phones to automatically charge, LED light, remove the load for 5-10 seconds later LED lights out in turn. The size is very small, perfect for promotional giveaway.