SFP+ Cables do only optical to electrical conversion

XENPAK was the first MSA for 10GE and had the largest form factor. X2 and XPAK were later competing standards with smaller form factors. X2 and XPAK have not been as successful in the market as XENPAK. XFP came after X2 and XPAK and it is also smaller.The newest module standard is the enhanced small form-factor pluggable transceiver, generally called SFP+ Cables. Based on the small form-factor pluggable transceiver (SFP) and developed by the ANSI T11 fibre channel group, it is smaller still and lower power than XFP. SFP+ has become the most popular socket on 10GE systems.10gtek SFP+ Cables do only optical to electrical conversion, no clock and data recovery, putting a higher burden on the host's channel equalization. SFP+ modules share a common physical form factor with legacy SFP modules, allowing higher port density than XFP and the re-use of existing designs for 24 or 48 ports in a 19" rack width blade.