AB Shutter 3 is a small remote shutter.
It connects to your handset as a Bluetooth keyboard. But which key codes does it send to the device?
To answer this question, I simply connected the shutter to my Android device, started an editor and pressed the buttons.
The button iOS sends the keycode Volume Up. The button Android sends the keycode Enter + Volume Up.
Be aware: it is possible, that there are some other key codes sent that went unnoticed.