We use the 19 hour candles for two reasons. They are short and fat and will stand on their own (unlike the tall skinny house candles) and are therefore easy to use anywhere. Also they are not too bulky and two of them provide well over 36 hours (or 3 nights) of use.
When using candles be aware of the fire risk and make sure they are safe from falling over and clear of combustable materials. See safety brochure.
The price is for one candle.