This is a LC duplex loopback connector. This is made from OS2 cable which has a core size of 9 microns OS2 is a standard single-mode optical fiber commonly used with wavelengths of 1310nm and 1550nm (9/125 microns), and has a maximum attenuation of 1dB/km. The OS2 standard is defined in ISO/IEC 11801. This adapter is best suited for fiber testing. Our patch cables are 100% compliant for all of your networking needs. Our products are guaranteed by federal law to not affect or void OEM warranties.