Wax formula, wick size, and other features were specially engineered to make these the ideal candles for UCO lanterns. Other candles can "melt down" prematurely due to improper wax formula and can leave significantly more soot on the heat shield compared to these. Each of these candles burns for 9 hours plus. They are made of citronella and paraffin with a special wax formula for optimized burning. The high melting temperature minimizes dripping and special cotton wick provides ideal flame with less smoke and a pleasant aroma.