Default value of PreferredBackBufferWidth and PreferredBackBufferHeight (XNA 4.0)?

If I don't set values into PreferredBackBufferWidth and PreferredBackBuffe开发者_如何学CrHeight, window game also display. So what are these default values ?

Launching various sample apps from XNA 4.0 and VS Express 2010 for Windows Phone, they tend to be 854 for the default width and 480 for the default height. This is probably because the XNA team really wants to focus more on Windows Phone 7 development and an ideal resolution to test WP7 programs is 854x480.