LC FIBER KEYSTONE INSERT is compatible with Multimode OM1, OM2, OM3, OM4 and 50 micron or 62.5 micron fiber patch cords; Fits a standard opening in a patch panel, wall plate or surface mount box for keystone jacks LC FIBER COUPLER joins two duplex multimode fiber patch cables with low profile LC connectors; Protective dust caps on the adapter prevent dirt from contaminating the fiber keystone jack or multimode fiber cables DUPLEX LC ADAPTER with a flangeless design, phosphor bronze sleeve, and stainless steel retention clip accommodates zipcord fiber cables; Fiber keystone will not block the zipcord yoke when changing polarity of the cord