The FITB13758GMN | FS1306B from Fiberinthebox is a Fiber Optic Attenuator with Attenuation 0 to 50 dB, Attenuation Resolution 0.01 dB, Insertion Loss <1.5 dB, Return Loss 35 to 40 dB, Operating Wavelength 1310 nm, 1550 nm. More details for FITB13758GMN | FS1306B can be seen below.