Announced at the Surface 2 launch event in September 2013, the Power Cover is the last generation 2 Surface accessory to ship to customers. Basically a Type Cover with a built-in battery, the Power Cover promises to dramatically improve your Surface 2, Surface Pro or Pro 2 battery life at the expense of a bit of additional weight.

If you've been waiting on the Power Cover—it's especially desirable for the battery life-constrained original generation Surface Pro—stop reading this and rush over to the Microsoft Store online. There, you can preorder the Power Cover for $199.99. It's supposed to start shipping next week, on March 19.

I'll be reviewing the Power Cover later this month if all goes well, but here's a rundown of what to expect.

Compatibility. The Power Cover works with the Surface 2, Surface Pro and Surface Pro 2. (But not the original Surface RT.)

Additional battery life. Microsoft claims the Power Cover will improve a Surface device's battery life by 70 percent. I'd be surprised if it was that even across each device, but I'll measure it and see how it stacks up in real world use. (At the launch, Microsoft used the figure 50 percent better battery life.)             

Type Cover design. The Power Cover looks and works just like a Type Cover 2, though it lacks the backlit keys that make that keyboard cover so nice. Microsoft says this is to save battery life, which is of course the point of this accessory.

Additional weight. The Power Cover weighs 1.2 pounds, or about twice the weight of a Type Cover 2. This sounds reasonable on paper, but I'm curious to see how it feels comparatively out in the world. And here's another way to think about this: Combined with the original Surface Pro, the total street weight is 2.7 pounds. That's a bit below the Ultrabook average of 3 pounds, but a bit more than a comparably sized device, like the MacBook Air 11-inch, which weighs 2.4 pounds.

Additional thickness. Additionally, the Power Cover is (as you'd expect) thicker than the Type Cover 2: 9.75 mm vs. 5.4 mm.

Colors. The Power Cover comes only in black. I guess people who want more battery life are serious people.

Availability. The Power Cover is available to customers in the US, Canada and Japan only. (Thanks to Mary Jo Foley for that bit.)

More soon.