T5 can support the 2nd screens of 9.7", 11.6", 12.1" and 15.6";

the main screen for a standard T5 is in 15.6",  1920*1080 of resolution, with 1366*768 optional; for Copy mode of the display, the resolution of the main screen and 2nd screen must be the same. For the extended mode display, it is no issue to have different resolutions of the main and 2nd screens.