SFP (Small Form-factor Pluggable) modules can be either copper or fiber, depending on the type. Copper SFP modules use RJ45 connectors and are designed for Ethernet over copper cables (Cat5e/6). Fiber SFP modules use optical fiber cables with LC connectors, supporting longer distances and higher speeds compared to copper modules.the fiber SFP runs at 40°C (104°F) while the copper SFP should run around 52°C (126°F) in the same environment.