Latest M180 integrated nozzle cooler on extruder. If you purchased M180 without nozzle cooler, you can still DIY to add to your machine.
Please check model and x3g for cooling support. There is a hanging wire (12V power for fan) hidden in front right corner of M180, you can connect to an external 12V fan.
To enable cooler, please reference to: http://wiki.malyansys.com/doku.php?id=enable_pwm_feature_for_cooling