I have been doing a little research in helping a family member buy a new mower. I am trying to tell the difference between the series of Kawasaki motors. Their website is fairly ambiguous. Here is the best that I have come up with: FR - Homeowner series FH- Standard Commercial Series FH-KAI - Same as FH, but with heavier duty air filtration FX- Top of the line Commercial Series with heavy duty air filtration and an larger oil cooler. FS - ??? Any additional information or corrections would be most helpful.