....to use on what?  If you are replacing an EI, some are swappable with the RCEXL ignition, and some are not.  Some hall sensors need exposure to one side of a magnet, or the other pending the brand as well.  Timing can also be an issue pending what you are doing with it.  I would suggest giving as much information as you can, about what you intend to do with the ignition, and there will be plenty of help here to guide you along. 

I might also recommend for very good quality ignition Q and A....contact www.CH-ignitions.com