A free app for Android, by Wayne Piekarski.
This is a plugin for X-Plane 11 that allows you to view and manage multiple textures for the HSI, CDU, and other displays in-game. It works in both portrait and landscape mode, and you can arrange your phone in any way you like. It's easy to use and very intuitive, so you won't have any problems using it.
It supports all the textures that are available for the HSI, CDU, and EICAS displays. It also supports the EICAS TFR (traffic flight reference) and CDU (cared for department of the unit) displays, as well as the EICAS/CDU and HSI displays. It works on both Android and iOS devices.