This leg is only 10" wide and a popular accessory for the Stel'Air Magnetic Pedal Exerciser.
Install it on the front OR the back. The narrow width will fit between chair legs easier which means you can bring the pedaller closer to your chair while you work out.
The standard legs on the Stel'Air Magnetic Pedaller are 15" wide. This is so the bike remains stable during use. People with shorter legs may need to bring the pedaller closer for more comfortable motion.