For some consumers , for some people , when  they see a folding Smartphone which can unfold to a   15.6 inches screen size to  become a   15.6 inches  Tablet [ 1 2 ] , they love it very much . The main reason I believe is  that for some people who want only one computing device , 15-inches screen size hits the sweetspot .  It's the minimum screen size to achieve the kind of usability , required in having only one computer ,  required in having only one machine .   And  that one machine ,  and that one computer ,  that one computing device could be  a  folding Smartphone (a  folding smartphone which can unfold into a  15.6 inches Tablet)  or  a   15.6 inches  Cellular Laptop (360 degrees foldable/detachable) whereby both of these machines can  unfold into a   15.6 inches  Tablet ,  whereby both of  them can be used  as a  Laptop or as a Tablet  or  as a  Smartphone .