The CR-250 replaces the CR-240. This is an American made wax refill with an excellent burn that should last for appx. 2.5 hours. It is 5.75'' long, so it will fit in all sizes of mechanical candles. Made of high quality wax, just slide this wax refill into your mechanical candle, light it and put your worries away. Easy clean up and a great price that makes them affordable to use over and over again.