The SC slot and the ExpressCard slot are not the same. I have a Latitude E6410, and it has both a smart card (SC) slot on the left side and an ExpressCard (EC) slot on the right. The EC slot is about 3 times thicker. The smart card slot is for reading smart cards (http://en.wikipedia.org/wiki/Smart_card), and are a way to verify someone's identity to allow them to use the computer, and are common with the government and various companies. The Express Card (http://en.wikipedia.org/wiki/ExpressCard) slot is for expansion devices, like wireless cards or USB 3.0 ports. ExpressCard is the newer and much faster replacement standard to old PCMCIA cards.