Specially developed to aid with frost protection providing sufficient heat will provide sufficient heat to keep small greenhouses and cold frames frost-free while saving energy costs. A 2-function 'mushroom' lid stores heat from the candle. Keep well away from combustible material. Terracotta Heater - The Firefly candle holder is specially developed to aid with frost protection and will provide sufficient heat to keep small greenhouses and cold frames frost-free. Save energy costs with environmental-friendly heating and only light the candle (not supplied) when your plants need to be protected from frost. Mushroom-shaped lid has two functions - it stores the heat from the candle, and can also be filled with a variety of scented oils. Heater Candles - Conservation of resources and CO2 avoidance are convincing arguments in favour of Firefly biomass candles. Made from Bio-mass and a truly sustainable alternative to paraffin. No petroleum is used to make Firefly candles and the rainforest is left untouched. No raw materials are used that could otherwise be used as food or animal feed. Heating power per candle approximately 40 watts. Burning time approximately 48 hours. Dimensions of each candle 10cm high x 6cm diameter. Weight 200g.