BriskHeat Plastic Drum Heater - 55-Gallon, 300 Watt, 120 Volt, Model Number DPCS15: Drum And Pail Heaters: Amazon.com: Industrial & Scientific
Powerblanket Insulated 55-Gal. Drum Heating Blanket - Barrel Heater, Fixed Temp 145°F, Freeze Protection, Process Heating PBL55F - The Home Depot
BEAMNOVA Metal Drum Heater 110V Pail Heating Band for 55 Gal Barrel 5 * 68.5 inch Honey Oil Silicone Rubber Heating Band Heavy Duty Temperature Controller: Amazon.com: Industrial & Scientific