The black colored MTP/MPO adapter has

MTP/MPO loopback modules are used

Adapters are installed in optical patch

Adapters are pass-through sockets and

ST to LC SM DX Fiber Optic

This LC male to ST female duplex

LC / UPC to LC / UPC 4-core single-mode

The key to fiber optic connection is

Closet Connector Housing (CCH) Panel,

LC duplex plastic fiber optic adapter