Answer 2: Enamel is the hard material that coats your teeth, and is made mostly of a mineral. However, we call other things enamel. There's enamel paint, which is totally different, and there's also porcelain enamel, which is used to make a lot of dishes.
All of this is due to Amazon's unique approach with the Echo. It's not a portable speaker like we've seen from Jambox and Logitech. Instead, it's a rather large, cylindrical device that needs to be plugged into power. It's something you'll likely just leave in a single spot in your home.
And this is where the Evo comes into play. (Such a long-winded introduction!) Evo is a portable battery pack for the Echo Dot that has the same round shape, magnets to hold it to the Dot, LEDs to indicate battery level, and a minimalist MicroUSB plug that doesn't dangle and goes right into the Dot.