The PMOCIR-4-A from COMCORE Technologies is a Fiber Optic Circulator with Directivity 50 dB, Insertion Loss 3.8 to 4.2 dB, Isolation 45 to 52 dB, Operating Temperature -5 to 50 Degree C, Optical Power 300 mW. More details for PMOCIR-4-A can be seen below.