Cisco 4OC3X/POS-MM-MJ-B

The Cisco 4OC3X/POS-MM-MJ-B is a line card module designed for use in Cisco 12000 Series routers. It provides four ports of OC-3/STM-1 (Optical Carrier level 3/Synchronous Transport Module level 1) connectivity using a pluggable Small Form-Factor Pluggable (SFP) interface. The "MM" in the model name stands for multimode, indicating that it supports multimode fiber optic cables. The "MJ" refers to the type of SFP connector used, which is a duplex SC connector. This line card module is used for high-speed data transmission over optical networks.