Technical documentation for Shimano FC-M510
That is an older style octalink crankset.  The documentation is available here for the octalink version and here for the square version.  As to what size BB you'll need that will depend on your frame.  There are several sizes of octlink BBs available depending on how your frame was manufactured.  If you don't have your old BB available with a legible size on hand, I would recommend taking the frame and cranks into a shop and having it measured so they can order you the correct size.