Correct - 303 is a different sort of stuff. I use the standard 'aerospace protectant' on my sit on top kayaks (polyethylene - roto molded). BUT they make various other products too depending on the intended application.
I was gonna link to the older 303 post, but I see that Donna already did.
If anyone is interested they offer a 'FREE' (for $5.00 postage, of course) sample kit of several of their products and literature. I recommend the sample kit as an inexpensive way to at least become familiar with what 303 is as compared to the typical "Armor All" type products. There's tons of info on the direct website too -
www.303products.com - rather than just reading from someone else's sales link.
I can't speak for use on
fiberglass, or on FGRVs (haven't even got one yet...... yet) but for what I use their products for, for sporting and automotive applications, 303 is great.
hope I don't sound like an info-mercial. I'm not a paid spokesman - just a convinced consumer.