MPO fiber optic coupler provide a fast and easy way to connect one male MPO fiber cable (with alignment pins) to one female MPO fiber cable (without alignment pins). Constructed of light weight yet durable plastic, these couplers can be mounted in a 0.6" X 0.4" panel cut out. They can be used with MPO connectors that have 4, 6, 8 or 12 port ferrules. The couplers have an adjustable keyway that allows them to change keyway orientation between Key Up to Key Down for straight wiring or key up to key up for cross wiring applications. Couplers are suitable for both multimode and single mode applications.