Uses OEM parts.  Easy install for those who would like to add the 4th wheel between the rails of their 2019 + Arctic Cat or Yamaha with the 25mm axle shaft.
 
SImply replace your existing long spacer tube and washer on the inner part of your axle with the included shorter spacer tube, wheel, and plastic wheel-axle spacer block.  No modification of existing parts.  Easy conversion back to original if desired.  ISR Stock class legal.
 
This kit is the spacers only.  It does not include the wheel.