The PTP 650/670 provides three flexible input/output (I/O) port options - a PSU port, an SFP port, and an auxiliary port. The SFP port supports both a single-mode and multi-mode optical interface as well as a gigabit Ethernet interface. To order either an optical module or the gigabit Ethernet module, you need to specify which SFP kits you require. Each SFP kit contains an SFP module, gland, software key, and documentation. One kit is required per ODU (two kits per link).