The S/FTP cable, Screened Foiled Twisted Pair (S/FTP or SFTP), is an improved variant of the FTP cable. Unlike the FTP cable, the S/FTP cable has much better shielding properties because it has two shields: a foil shield and a braided shield.
Like the FTP cable, the S/FTP cable has four twisted pairs of wires. There are two versions of the S/FTP cable: in one version, each pair of wires is covered by a foil shield. This version, in which the four pairs of wires surrounded by a foil shield are together surrounded by a braided shield, corresponds to category 6/7. Frequencies of 250 MHz (cat 6) and 600 MHz (cat 7) can be transmitted via data cables of these categories.
In the second version, the four pairs of conductors are jointly surrounded by a foil shield and a braided shield above it. This version corresponds to category 5e( Cat 5e), which is characterized by better Near End Crosstalk( NEXT). The foil shielding is made of aluminum foil and is particularly efficient at higher frequencies, while the braided shielding above is made of tinned copper braiding. The double shielding improves electromagnetic compatibility( EMC) and reduces electromagnetic spill and interference.
Above the braided shielding there may be a thermoplastic shield and above that the cable sheath, which is usually made of polyvinyl chloride( PVC). As with all STP cables, the signal-carrying wire pairs are color-coded.