Tell me more about 303

In my experience, 303 is a coating to make the rubber and vinyl shine once it's wiped-off. I prefer the natural black tire look, not the shiny, black shine. So, after trying many products, I settled on Greased Lightening spray cleaner, then rinse with water for that beautiful, natural showroom clean black, matte look that represents the tire as cleaned without a plastic coating look that attracts and gathers dust and dirt, as well as rinses off when the tires get wet from rainwater. Another home remedy for exterior plastic vent shrouds I discovered last year quite by trial and error is pure liquid bleach wiped and rubbed on these surfaces like hatch canopies and your refrigerator and stove gas vents on the roof. It cleans like magic any dry, brittle and stained rooftop vents that are plastic.