When I shot fixed pins, I had a system I used to get yardage that was pretty much the same thing as this product. I talked about it here years ago. I would use the pins on the bow to size up the target or deer and get pretty doggone close to the yardage. I would set one pin at 20 and one at 40, and those are the only two pins I used. After a while of shooting, I just learned where my pins were positioned in relation to the size of the target and then that gave me a pretty close estimate on where to hold.