I'd be leery over the inconsistency over that ads.  Although the title said OEM, description says XFORM brand, no direct picture over the Dell OEM label or part number, and no customers review. When shopping for a 500w PSU compatible with your OptiPlex 7070, look for power supply with these part number Y7R0X 500W (made by Chicony), 99TPH 500W (made by Liteon), and 5K7J8 500W (made by Delta), credited to redxps630. Similar discussion can be viewed here.
Saw this OEM Power Supply 500 Watt on Amazon.ae, can anyone confirm if it works fine on Optiplex 7070mt? Thanks.
PSU for optiplex 7070 mt