13-13.5 Inch: Internal dimension: 13.5" x 9.3". Compatible with 13 Inch Tablet Laptop: 13-13.5 Inch laptop: 13 Inch Macbook Pro Retina / MacBook Air, 13.5 Inch Surface Book and Most 11-13 Inch Ultrabook Netbook Laptop Macbook
12 Inch: Internal dimension: 12" x 8.6". Compatible with 11-12 Inch Tablet Laptop: 12 Inch Apple Macbook, Microsoft Surface Pro 6 4 3, Surface Pro 2017 and Most 11-12 Inch Chromebook Ultrabook Notebook Laptop