Wikipedia
SxS
SxS (S-by-S) is a flash memory standard compliant to the Sony and SanDisk-created ExpressCard standard. According to Sandisk and Sony, the cards have transfer rates of 800 Mbit/s and burst transfer rate of up to 2.5 Gbit/s over the ExpressCard's PCI Express interface. Sony uses these cards as the storage medium for their XDCAM EX line of professional video cameras.