The F-CPL-S12155 from MKS | Newport is a Fiber Optic Coupler with Wavelength 1550 nm, Insertion Loss 3.4 dB, Return Loss 55 dB, Polarization Dependent Loss 0.1 dB, Operating Temperature -40 to 85 Degree C. More details for F-CPL-S12155 can be seen below.