Here's one of the best I've found:
https://www.amazon.com/gp/product/B000GFHJUS/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1
Most manufacturers anticipate their being a bezel when they say what size laptop it's for (so they account for 13.5-15 inches or so of laptop when they say it fits a 13" device) so you should be fine looking at cases designed for 13-15" laptops. Just take into account that most laptops today have a 16:9 aspect ration on the screen where the Surface Book has 2:3, so you may needs something a little bigger to accommodate that or to find a case designed for that aspect ratio, since just saying something has a 13" screen is measured from opposite corners regardless of the dimensions of each side.