For DigiKey part number 952-G125-MH15005M4P-ND Harwin part number G125-MH15005M4P
The Extra screw part number is DigiKey part number 952-G125-4520000B-ND Harwin part number G125-4520000B.
Link to Harwin part number G125-MH15005M4P: Gecko-SL Male Horizontal Conn. - G125-MH15005M4P - Harwin
After clicking the link, go down the page to the RELATED PRODUCTS, click on Accessories & Tooling you will see the part number G125-4520000B as the Screw-Lok Bolt.
Link to Screw Lok Bolt: Gecko-SL, MT Mounting Bolt - G125-4520000B - Harwin