Our FC fiber optic attenuators are UPC and APC types, FC fiber attenuators are Low Polarization Dependent Loss and a stable and independent wavelength distribution. Basic types of fixed attenuation include single mode, dual window and multimode in D4/PC, FC, FC/UPC, MU, SC, SC/APC and UPC, ST and ST/UPC style connectors. Optical attenuators usually work by. Fibertronics, Inc. Use the filters on the left of the page to find the product you require. By offering a direct-from-factory manufacturing model, we provide flexible OEM/ODM solutions—including custom branding and specific.