flangeless, clip-in: Some adapter bodies have a flat plate (“flange”) with screw holes or clip slots, while others have snap-in clips. A fiber-optic adapter — sometimes called a coupler or bulkhead coupler — is a passive mechanical interface that mates and aligns two terminated optical fibers (i., two fiber connectors) such that light can reliably pass from one to the other with minimal insertion loss and maximum return loss. SDX Metal Fiber Optic Adapter Plates work with wall- or rack- mount SDX enclosures and Leviton multimedia adapter brackets. SDX Adapter Plates are available in LC, Shuttered LC, MTP®, and QUICKPORT snap-in connector styles. In most applications, the Closet Connector.