The PMC1550-50B-FC from Thorlabs Inc is a Fiber Optic Coupler with Wavelength 1550 nm, Directivity 55 dB, Insertion Loss 3.6 - 3.6 dB, Operating Temperature -20 to 70 Degree C, Storage Temperature - 40 to 85 Degree C. More details for PMC1550-50B-FC can be seen below.