It isn't just a gas cap replacement. You have to send them your generator and they remove the gas tank and replace it with the gas regulator and replace the gas cap with a quick disconnect for a propane or natural gas line. It's the same conversion but everything mounts inside the generator and you can't switch back to gasoline. Looks better but isn't as versatile and costs more.I took a peek at their web site. I like the concept of how they use the old fuel cap to plug in the propane. Unlike other conversion kits for the yamaha ef2000is units that have a big gas regulator that bolts to the side of the case, making it awkward to cover / store.
I would like to see a natural gas conversion kit for my needs.