Above is a video of my husband using a key to turn my expander for the first time after SARPE surgery. This is to demonstrate that it was not a painful process at all. You might feel some pressure, but not pain. It is recommended to take Advil/Ibuprofen 30 minutes prior to having this done.
Below is a close-up of the bonded expander in my mouth. This photo was taken before any activation had taken place. You can see the small holes and the arrows indicating to turn to the back of the mouth.
Here is another video of my husband explaining how to turn an expander. This video actually demonstrates how the expander is activated, and how to use the key for activation: