Hey Joe, the powerflow is the bagger system for the 2320. There is an plastic impeller unit that connects the deck with one of the blade pulleys. There is a pulley belt that routed around the pulley and when the mower blades is spinning, so is the impeller for the grass catcher. It sends it up through plastic shoot and into the bags in the back of the machine, Its a nice setup. I have one on my 585 GT. I can imagine the setup is very expensive. If I remember correctly, my unit was $1200.00. Russ