What is neck height on wick assemblies?

On each wick base there is a neck that supports the wick and holds it in place. In most instances the neck height can run as low as 3 mm to as long as 9 mm. The type of candle and jar being used will determine the neck height. It has always been recommended with gel candles that the 9mm neck be used. Many candle companies have also gone to 6 mm and 9 mm necks for their paraffin candles as well.