# item.guide
Side-by-Side Comparison Fiber Connectors

FC vs. ST

Comparing 2 standards across 10 specifications. 9 key differences identified.

Comparing:
FC
ST

The FC connector (Ferrule Connector / Fiber Channel, TIA-604-4 / FOCIS-4) is a heavy-duty optical connector designed by NTT. Utilizing a 2.5 mm ceramic ferrule inside a threaded round nickel-plated metal coupling nut, it provides extreme mechanical retention in high-vibration environments and optical test instrumentation.

View full FC spec sheet →

The ST connector (Straight Tip, TIA-604-2 / FOCIS-2) is a legacy fiber optic connector developed by AT&T Bell Laboratories. Featuring a 2.5 mm spring-loaded ceramic ferrule with a BNC-style twist-and-lock metal bayonet coupling, it remains common in industrial networks and campus multi-mode backbones.

View full ST spec sheet →

Specification Comparison Table

10 Parameters
Parameter / Spec
Standard / FOCIS
TIA-604-4-B (FOCIS-4) / IEC 61754-13 TIA-604-2-B (FOCIS-2) / IEC 61754-2
Ferrule Diameter
2.5 mm 2.5 mm
Ferrule Material
Zirconia ceramic Zirconia ceramic or stainless alloy
Latching Mechanism
Threaded screw-on metal coupling nut Bayonet twist-lock (BNC-style keying)
Fiber Modes Supported
Single-Mode (OS2) and Multi-Mode Multi-Mode (OM1/OM2 primarily) and Single-Mode
Typical Insertion Loss
0.15–0.30 dB 0.25–0.40 dB
Keying Mechanism
Adjustable / fixed alignment key
Polish Types Available
UPC (Flat metal body) and APC (Step-keyed / cone body)
Polish Type
PC / UPC (Round metal housing)
Mating Cycles
500+ cycles