A 6.8Ohm, 3 watt power resistor is included in EVERY kit. We have found these to be very reliable and can provide more than the required amount of heat for extrusion of ABS and PLA plastic. Additionally we have a heater cartridge available for an additional $14. It is a professional grade, 12v / 40 w heater cartridge with insulated leads. It can get to extremely high temperature, stably and safely; it also offers a 'cleaner' looking installation with the sheathed wiring. For those that want to experiment with high-temp materials, the heater cartridge upgrade is worthwhile.