The 2×2 1490 & 1550nm Dual Window Singlemode FBT Coupler Splitter With Steel Tube is a high-performance optical splitting and combining device engineered for reliable operation across the 1490 nm (E-band) and 1550 nm (C-band) wavelength windows. Utilizing advanced Fused Biconical Taper (FBT) technology, this coupler splitter delivers low insertion loss, accurate coupling ratios, excellent wavelength stability, and consistent bidirectional optical performance in dual-wavelength singlemode fiber systems.