This is a replacement E3D V5 heater block which is used in the E3D V5 hotend for both the 1.75mm version and the 3mm version.
The heater block is basically a small billet aluminum block. It has a CNC drilled and tapped thread all the way to the top that accepts the V5 thermal break and E3D nozzle. It also has CNC drilled holes that accept the heater cartridge as well as a 100k 100 1% NTC thermistor. The heater cartridge is used to heat the heater block to the desired temperature, which in turn heats the hot end of the heat break and nozzle allowing for smooth filament extrusion. The thermistor is used to read and monitor the temperature of the heater block, allowing for precise closed loop PID temperature control.
