I have been looking for a foldable BT keyboard for a while. Almost of my computer use consists of using Emacs, a terminal and the Chrome browser. Using the Tmux terminal emulator app, I have got Emacs to work on my Fire tablet. A 7" screen is fine for writing and reading text. When I use Emacs, all my input is via the keyboard, no mouse required. However, most Emacs functions use the Ctrl and Alt keys in combination with another key (e.g. Ctrl-x-s for saving a file), which is almost impossible using an on-screen keyboard.
This keyboard is robustly built, with a metal outer. The latching mechanism looks as though it will withstand lots of abuse. The keys themselves have a nice action and the spacing about the same size as my Dell XP notebook, so it's nice to type on.
The keyboard folds down into a pocketable size. Now instead out taking my expensive laptop out with me, I can achieve the same functionality with a cheap Android tablet.