We apologize, but this item is no longer in production. ELEY does not offer a suitable replacement; however, you should be able to find the same screw (without the button head) at most local hardware stores. A hex or Phillips head screw will work fine.
Use the following specifications to find a suitable substitute at your local hardware store, 1/4-20 X 5/8-inch screw. Although the original was stainless steel for corrosion resistance, the replacement does not have to be.