The 2×2 1310nm Single Window Singlemode FBT Coupler Splitter With Steel Tube is a high-precision optical splitting and combining device designed for stable and reliable operation at the 1310 nm O-band wavelength. Manufactured using advanced Fused Biconical Taper (FBT) technology, this 2×2 coupler splitter ensures low insertion loss, accurate splitting ratios, excellent wavelength stability, and consistent bidirectional optical performance in singlemode fiber networks.