100G CFP2/CFP4 optical transceivers are commonly used as 100G Ethernet interconnects and deliver higher transmission efficiencies than CFP optical transceivers. While electrical similar, they specify a form factor of 1/2 and 1/4 respectively in size of CFP. CFP, CFP2 and CFP4 modules are not interchangeable, but would be inter-operable at the optical interface with appropriate connectors.