Microsoft has provided a ship date for its promised Surface Power Covers: March 19, 2014.

The disclosure of the date ocurred on March 10, which is when Microsoft went live with pre-orders for the covers that extend the battery life of Microsoft's Surface Pro, Surface 2 and Surface Pro 2 tablets. (I saw the pre-order page on the Microsoft Store thanks to a tweet from that account.)

The Microsoft Store pre-order page claims the Power Covers -- Type covers with extra battery support -- will extend battery life by up to 70 percent. (Microsoft officials were promising battery-life extension of up to 50 percent from the new covers last year.)

The Power Covers weigh .55 pounds and are 9.75 mm thick, according to Microsoft's page. They don't have back-lit keys, unlike the new Surface Type 2 and Touch 2 covers. They will retail for $199.99.

Update: The weight information on Microsoft's page is wrong. The Power Covers weigh 1.2 pounds, Microsoft officials confirmed on March 11. The thickness listed is also incorrect; word is that it's actually double the listed number.

Microsoft announced plans to provide Power Covers for its Surfaces in October 2013 when it launched the second version of its ARM- and Intel-based Surface devices. At that time, officials said Power Covers would be available in "early 2014." Microsoft execs declined to provide any further updates about the timing on the covers since that time.

Microsoft has had issues keeping its Surface tablets and associated peripherals in stock. The Surface docking stations have gone in and out of stock since last fall .

I've asked Microsoft execs whether the Power Covers will be avaialble in areas other than the U.S. as of March 19, and if so, when. I will update this post when I hear back.

Update: The Power Covers will be available initially in the U.S., Japan and Canada, a Microsoft spokesperson confirmed The company is not sharing names of specific retailers or international availability beyond that at this time.

In related news, WPCentral.com is reporting that Microsoft brick-and-mortar stores are starting to receive stock of promised LTE-enabled Surface 2 devices. Last fall, Microsoft officials said those devices would be available in the early part of 2014 initially on AT&T and Vodafone.