Couldn't find any help to get the right size. So I googled and found a seller who explained the dimensions to me. The roller stem bolt failed to determine the stem size. Another seller offered to take it to a hardware store. Sure enough. They had found a few options that fit in bold so they knew the size to order a standard screw. As for the length, just measure the length of the stem. It would be VERY USEFUL if this were suggested here. I would prefer these videos. Better done but Outwater Premium is not the right size.