This 1U PCI Express 16X VGA Riser Card can be used in most 1U and 2U cases (B position slot on M/B).
It goes into B position PCI Express 16X slot on your M/B.
If the PCI_E 16x is at A position(7th slot), the extender should be needed
Please see the picture below for reference:
4U Rackmount EJ-4U6518S-C
1U Server EJ-104
3U Rackmount EJ-3U488.P350
Power Supply DP-50X-C617-BX
Power Supply | Rackmount | Server Chassis | Data Storage | Mobile Rack