Ignition sources. That C&H ignition system, while I have had no experience with it it would appear to be the one of choice for most gas engines that I come across. However with Saitos all of them with the exception of one still run their original saito systems. The one that was replaced with a RXELL unit was done so as the result of operator error (his admission) causing the unit to burn out. I follow the trials and tribulations of saito gas operators and find reasons not to fire mine up.