All you should know about ST Fiber Optic Connector

What is ST fiber connector?

ST connector meaning “Stab&Twist” connector, the housing is round and the fastening method is a plug-in snap-on, i.e. snap-on circular interface. The ST fiber connector has a bayonet mount and a 2.5 mm long cylindrical ceramic (common) or polymer ferrule to hold the entire optical fiber, which is mounted similarly to a snap-on bulb that is inserted and then rotated half a turn into the bayonet to hold it in place.

 ST connector fiber is developed by AT&T, the main parameters and indicators and FC and SC connectors are comparable, but in the company’s applications are not common, usually used in multi-mode device connection, and other manufacturers of equipment docking use, commonly used in fiber optic distribution frame.

ST fiber optic connection applications

ST connector can be used in different application with different version, like to connector with fiber optic cable, to match with adapter and attenuator, or even to use on ODF or NAP CTO boxes, like below:

ST fiber optic patch cable SMF            ST fiber optic cable MMF

ST fiber optic connector               ST fiber optic termination kit

ST fiber optic adapter                 ST fiber optic attenuator  


ST fiber optic patch panel             ST fiber optic termination box

Frequently Asked Questions

  • How can you tell the difference between and ST and an SC connector?

ST and SC interfaces are two types of fiber optic connectors, both use 2.5mm ceramic ferrules. But ST is metal housing with bayonet design, SC is plastic housing with design. The size and structure to connected with adapters are different.

For application 10Base-F connection, the connector is usually ST fiber, for 100Base-FX, the connector is SC in most cases.The core of ST connector is exposed, and the core of SC connector is inside the connector.

  • Are ST connector still used?

Yes, now the most popular connectors are SC LC due to they are more cost effective and lighter, but ST still used in some places like ODF and some multi-mode fiber conditions.

  • What is the ST type port?

ST port means the interface of fiber optic box, it is round shape, which is the same size as the ST connector head outer diameter. For example, ST fiber optic patch panel with 12 port ST port, that means this patch panel will deliver with 12 pcs round ports for ST connectors termination and distribution, in this box, you can only use ST fiber optic pigtails or adapters to make it compatible with. Below is 12 ST type ports adapter plate for 1U 12 cores rack mount ST patch panel.

  • What size of ferrule does an ST connector have?

ST connector use 2.5mm ceramic ferrule, same as SC FC connectors, the ferrule end face can be UPC PC or APC, depend on the fiber which used or project requirements.

  • How to distinguish single mode or multimode of the ST connector?

ST connector main body is metal, so the only way to distinguish is to use different colors for plastic boot. Yingda default colors are single-mode yellow or red, and multi-mode black.

But the color is not fixed, you can change as your wish, please specify when you place purchase order to us.

  • Is ST fiber optic connector can do APC?

Yes, of course. The APC ST connector boot is default green, UPC ST connector boot is black boot.

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