POFLink's X2 is a standardized factor for 10 Gb/s fiber optic transponders that is used for data transfer rates 10.3 Gb/s to 10.5 Gb/s. It is protocol-specific: Either 10G Ethernet or 10G Fibre Channel versions are available. X2 transponders are used in datacom optical links only (not telecom), and they are smaller than old generation XENPAK transponders. Its electrical interface to the host board is also standardized and is called XAUI (4 x 3.125 Gb/s).

POFLink manufactures X2-10G-SR 300m, X2-10G-LR 10km, X2-10G-ER 40km, X2-10G-ZR 80km optical modules. All modules support Digital Optical Monitoring (DOM) function .