An Energy Tank (or E-Tank for short) is a special item that first appeared in Mega Man 2 and games after it. It looks like a can with a flashing "E" on it. It refills all of Mega Man's health. E-Tanks are usually in hard-to-reach places. In Mega Man 2, you can keep up to 4 of these at a time, but in all games after it, you can keep 9.