12v 40w Professional Strain Relief Heater Cartridge for 3D Printers (5mm OD)
Cartridge heaters are the industrial way to heat up your hot end.  They will heat it up faster, more consistently and look a lot nicer in the process than power resistors.  They are insulated with magnesium oxide and encased in a Type 304 stainless steel sheath that is 5mm in diameter.
