Either is used when one is required and there are multiple options, usually two. Can be used for more than two but only for two options.

If you’re being asked about a company and you

can say: “It can provide 150, or 400 amps of power.”

Again, in sentences like this is how it

should be, because saying either makes the options sound limited

even though there are multiple options. It will sound better if you say: “It

can provide 100, 150, or 400 amps of power.”