The printer uses what Wanhao calls a “MK11 extruder”. There's no real standard, but it is an improvement over Wanhaos previous extruders back to MK8.

The stock MK11 uses a 0.4mm MK10 nozzle and PTFE thermal barrier, but new aluminum heater block. The new heater block has deeper slots for the larger 24v heater cartridges and thermocouple. It still uses the same plastic feed system as the MK9.

https://groups.google.com/forum/#!topic/wanhao-printer-3d/TEdslEknny4