The ST-SM Series from Huihong Technologies Limited is a Fiber Optic Attenuator with Attenuation 0 to 30 dB, Operating Temperature -40 to 80 Degree C, Polarization Dependent Loss 0.2 dB, Return Loss 50 dB (SPC), 60 dB (APC), Wavelength 1310nm or 1550 nm. More details for ST-SM Series can be seen below.