FX-100 is a spray sealant. I use it at times as a final topper to a carnauba, in the same way I would use something like Aquawax.
To my eyes FX-100 has a bit more depth than Aquawax, but is also more finicky to apply. For that reason, I've been reaching for Aquawax more frequently than FX-100. Lately, I've been preferring ease of application over slightly better depth.