From what im aware, Hat Pads and Gen Pads fit them
You dont have to argue. Just assimilate the information and move on.
Oh, and there is a pad that fits perfectly. Air cured silicone, or “rtv”, once cured in place, fits the gap perfectly. 
Broad pads might work.
Right in I will put that on the list to try as well. Same with yomagic’s suggestion. I wish all the skywalkers took flow groove pads. My nickel skywalker does but that because one drop made the response deeper on that one. Love the feel of the nickel skywalker.