You found 3 products in Computer Networking Expansion Modules - Dell Business UK

Avocent Server interface module - Expansion module - serial (0636430017020) Expansion Module
RJ-45 Interface, Cabling: Serial
3 store offers from £54 - £64

StarTech.com (PCI2S1P) Expansion Module
PCI Interface, Cabling: Parallel, Serial
4 store offers from £20 - £27

Dell (770-10350) (77010350) Expansion Module

2 store offers from £63 - £74