PCI-E PCI Express 16X to 4X Riser Card Adapter Extender Flex Flexible Extension Cable Install PCI-E 16X device to PCI-E 4X slot freely according to dimension and position of computer case. Ideal for small computer & server case, like 1U & 2U. One end is PCI-E 16X female and another end is PCI-E 4X male.