I have Digi II - they don't use the bottom as a ref. point, but where you have them set for depth, then you can set a movement up in feet 3,5,7,or 9" and time in seconds that you want it to move up and then return back down. since these are my first set of riggers, we tried it a couple of times when thing would get slow. things still stayed slow. did not put any fish in the box while this was running. did not notice any extra drain on the batteries. no extra wear / tear on the riggers. They can be fun to play tricks on the crew. I did this once when no one was looking and set it up 7' /3 mins. then sat back down. it started it first move and the rod jumped up, my buddy quick grabbed the rod. I was laughing a little....