SFP+ Cables can further be grouped into two types

Optical modules are connected to a host by either a XAUI, XFI or SFI interface. XENPAK, X2, and XPAK modules use XAUI to connect to their hosts. XAUI (XGXS) uses a four-lane data channel and is specified in IEEE 802.3 Clause 48. XFP modules use a XFI interface and SFP+ Cables use an SFI interface. XFI and SFI use a single lane data channel and the 64b/66b encoding specified in IEEE 802.3 Clause 49.SFP+ Cables can further be grouped into two types of host interfaces: linear or limiting. Limiting modules are preferred except when using old fiber infrastructure which requires the use of the linear interface provided by 10GBASE-LRM modules Also known as Direct Attach (DA), 10GSFP+Cu, 10GBASE-CR,[25] 10GBASE-CX1, SFP+, or 10GbE Cu SFP+ Cables.
Direct Attach uses a passive twin-ax cable assembly and connects directly into an SFP+ housing. SFP+ Direct Attach has a fixed-length cable, typically 1 to 7 m (passive cables) or up to 15 m (active cables) in length,[26][27] and, like 10GBASE-CX4, is low-power, low-cost and low-latency with the added advantages of using less bulky cables and of having the small form factor of SFP+. SFP+ Direct Attach today is tremendously popular, with more ports installed than 10GBASE-SR.SFP+ Cables (Direct Attach) Now On Sale [20% OFF] -- Amphenol 10-Gigabit Ethernet SFP+ Direct Attach Copper Cables are available in lengths up to 12m everyday.