The Optional Swivel Wheel Axis Kit allows you to modify the Phoenix from a standard fixed front wheel to 2 swivel front wheels which improve maneuverability on pavement and tight indoor spaces. The Swivel Wheel Axis Kit fits into the forks for the single fixed front wheel.  Easily assembled, no tools are required. 8-inch wheels. The swivel wheel axis kit does not work well in gravel or grass and is not intended for running.