Sequential charging for two Canon LP-E19 or LP-E4N rechargeable Batteries LED Indicators display when batteries are charging and when theyfre ready to use. Overheating detection minimizes possible high temperatures and automatically shuts off the charger. Short Circuit protection prevents the charger and batteries from receiving excessive amounts of current. Surge protection circuits guards the charger from overcurrent or defective and shorted batteries. 120-240 V AC input allows for travelling and usage anywhere in the world.