The on/off button is located in the middle of the wheel. The user hooks the thumb around the hub of the wheel and presses the button with the index finger knuckle. To keep her balance she places her other arm around the backrest.
A remote control is available for e-motion wheels. But this user does not want to bring it along all the time, so she learned how to use the button on the wheel.
Invacare, invacare.com (last checked August 2020)