Measuring 2 3/4" in diameter, these caps are a unique yet functional addition for standard mason jar candles. This unique product makes jar candles burn even better and the special design acts as an air flow regulator which causes the candle to burn cleaner and more evenly while reducing soot on Paraffin candles. They also work for single wicked "Soy Wax" candles. Application of the Candle Cap to a new candle will result in a higher than normal flame that burns above the lid surface. Therefore, it is recommended that its use be delayed until the wax level has fallen one inch from the as-new level. Simply place it over the mouth of a jar candle after it has burned down at least about 1/2".