Since the 1990s, many small form factor (SFF) fiber optic connectors have been developed to fill the interest in devices that may fit into tight spaces and permit denser packing of connections such as fiber patch cables. Some are miniaturized versions of older connectors, built around a 1.25mm ferrule rather than the 2.5mm ferrule used in ST, SC and FC connectors. Others are based on smaller versions of MT-type ferrule for multi fiber connections, or other brand new designs.

Most of these SFF connectors have a push-and-latch design that adapts easily to duplex connectors. LC, MU, E2000 and MT-RJ would be the most typical small form factor fiber optic connectors.

1. LC Connector
LC is short for Lucent Connector, licensed by Lucent. LC connector may also be called "Little Connector". It resembles a typical RJ45 telephone jack externally, while a miniature version of the SC connector internally. LC connector uses a 1.25mm ceramic (zirconia) ferrule instead of the 2.5mm ferrule and add a push-and-latch design providing pull-proof stability in system rack mounts. LC connectors are highly favored for single mode applications such as high-density connections, SFP transceivers, XFP transceivers, etc.. Generally, LC connectors can be found in simplex and duplex, single mode and multimode versions.

2. MU Connector
MU is brief for Miniature Unit, produced by NTT. MU connector is known as "mini SC" and is popular in Japan. It has push-pull mechanism, utilizing a 1.25mm ferrule the same as LC connector. MU connectors' applications include high-speed data communications, voice networks, telecommunications, and dense wavelength division multiplexing (DWDM). They're also utilized in multiple optical connections so that as a self-retentive mechanism in backplane applications. MU connectors can be found in simplex and duplex versions.

3. E2000 Connector
E2000, as known as laser shock hardening (LSH), is a technology generally used in Telecom, DWDM systems. E2000 connector is also called LX.5 connector. It looks like a miniature SC connector externally, like the MU connector utilizing a 1.25mm ferrule. You can easily install, with a snap-in and push-pull latching mechanism which clicks when fully inserted. E2000 connector includes a spring-loaded shutter which fully protects the ferrule from dust and scratches. The shutter closes automatically once the connector is disengaged, locking out impurities which could later result in network failure, and locking in possibly damaging lasers. When it's connected to the adapter the shutter opens automatically. E2000 connectors are available in single mode and multimode versions. FiberStore provides both E2000 to ST fiber patch cable and fibre optic patch cables E2000 LC rich in quality and best price.

4. MT-RJ Connector
MT-RJ is short for Mechanical Transfer Registered Jack. MT-RJ connector's overall dimensions are comparable like a RJ45 connector. MT-RJ connector dose not make use of a 1.25mm ferrule, and it is design is derived from MT ferrule. It features a miniature two-fiber ferrule with two guide pins parallel to the fibers on the outside. The guides pins align ferrules precisely when mating two MT-RJ connectors. MT-RJ connectors are designed with male-female polarity which means male MT-RJ connector has two guide pins and feminine MT-RJ connector has two holes instead. MT-RJ connectors are utilized in intra building communication systems. Since they are designed as plugs and jacks, like RJ-45 telephone connectors, adapters can be used with a few designs, but are not required for all. MT-RJ connectors are available in duplex version only and multimode version only given that they use the two-fiber ferrules.