what is the slot labled SC above the HD on my Latitude E6420

what is the slot labled SC above the HD on my Latitude E6420 hp sc slot Security cable slot 2 Vent 3 External VGA monitor port 4 USB charging port 5 Two USB ports 6 Smart card reader Right hp cache status problem detected p212 in slot 5 The Express Card Smart Card Reader by HP is a slot-mounted card reader for Mobile Workstations that allows you to conduct secure e-commerce transactions

hpe 5945 2slot switch -Slot 1 - 9 AM to 11 AM -Slot 2 - PM to 2 PM -Slot 3