I've been using 303 for about 20 years and love it.
Years ago they had only 1 formula and my boat got sprayed with it from bimini top to trailer tires.
Now they "specialized" the formulas (I guess for bigger $$)
303 have been the only real UV protectant for rubber for years and I yet have to hear about other protectant.
303 is not as long lasting as wax and will wash out while driving in the rain, but the best part is "spray on, wipe off, no cleaning necessary"
Pretty good cleaner too.
The manufacturer is in the county I live in, but from what I check, their warehouse charge for the formula more, than our local automotive auto parts chain.
If you have fiberglass coach, I would advise to order 1 gallon bottle. You will love it.
I also use it for fiberglass whirlpool in my house, but have to wash greasy residue before filling up with water.
They don't recommend it on paint, but I was spraying my boat trailer and it shined dull paint.