This is the Ultimaker 2 integrated nozzle + heater block for 3mm filament. This part is also included in the Ultimaker 2 hot end bundle. It has a 0.4mm diameter....
This is the Ultimaker 2 hot end isolator. It is the connection between the PTFE coupler and the nozzle + heater block. It is also included in the Ultimaker 2...