This is a real cheap way to learn Mach3 easily, or to use to make your own pendant when used with a wireless keyboard.
If your a novice it will streamline the learning curve as well as cut time on using Mach3. Advanced users can use it as well to train others easily, or for quick reference.
Review them here Mach 3 Keyboard "Hotkey" Keyboard Shortcuts Video Explanation | eBay