Many in control line flying liked Fox engines and accessories. It was a blow to the community when Fox announced their model airplane business is gone forever. Regarding plugs, I bought a dozen Chinese 4-cycle hot for under $30, so far they are working fine for 2 cycle control line. I used to like Swanson Fireball Red (Hot), but I got a crop of them that only work for a short time, then go south. Must have been some bad, aged NOS stock.