Quoted from gcmess:
I have one at the end of my path of the dead. Helps the ball into the habitrail and from dropping on the plastic. Doesn't stop all the drops but keeps them to a minimum. Not sure it's suppose to be there but I like it. It is a little tight to the wall...but not a big deal.
I just have 2 crystal clear rubbers on a longer screw at the end of my POTD and am very happy with the way it works. I have taken them off twice and missed them both times and quickly put them back on. As a side note, I am also using the Arwen clear ramp and the ball still goes down the ramp into the Shire on occasion.