Panthera Footrest for S3 Swing comes in two versions: Footrest S3 Swing and Backrest S3 Swing Easy. 

Footrest S3 Swing 
The original Panthera footrest for S3 Swing models. Features a lockable swing-away mechanism operated by a push button.

Footrest S3 Swing Easy​
Ideal for users who prefer a solution where there is no need to operate a button. The footrest swings in or out effortlessly with a simple lift motion - no button required.