Senko 215-103-L1 Premium 125um Single Mode ST Fiber Connector with Blue Mini 3.0mm Boot.
The SENKO ST connector has a bayonet-style housing and a long spring-loaded ferrule hold the fiber. They are available in both multimode or singlemode versions. Horizontally mounted simplex and duplex adapters are available with metal or plastic housing, with a choice of phosphor bronze or zirconia split sleeve. SENKO also offers the epoxy-free ST XPFit connector for quick field termination. The ST is one of the older generations of connector, but is still widely used for multimode networks, including LANs for buildings and campuses.