Dell DSS 2500 Owner's Manual page 106

Figure 48. Installing a low profile expansion card into the dual riser module
1 low profile expansion card
3 dual riser module
Figure 49. Installing a low profile expansion card into the dual riser module
1 dual riser module
3 full height and full length expansion card
106 Installing and removing system components
2 expansion card retention latch
2 expansion card retention latch
4 PCIe slot on riser card