Because Cockpit Premium is designed to be used on the interior, the level of UV protection is very minor. This is because glass in today's vehicles already have UV filters in them. Therefore, it is not necessary to have maximum UV protection like what is needed on the exterior.
On the other hand, Tiefenpfleger Vinyl/Rubber Care is designed to be used on the exterior as well so it has maximum UV protection in it.
Personally, I use Tiefen on the interior occassionaly to keep the components in the best condition possible. I use Cockpit Premium on a regular basis for general upkeep (minor cleaning, dust removal, etc).
As far as a UV protection is concerned in relation to 303, I honestly do not know how it compares. I do know that we source our UV protectants from a quality source. At 1Z we formulate all of our products with the best raw materials available which is why products like our polishes do in one step what some other brands do in multiple steps. We don't count pennies... We've never really put a lot of emphasis on charts, graphs, etc... as they say "the proof is in the pudding" (how did pudding ever get involved). We've had a very good track record with the product in the past years especially from people who use it often - detailers.
Anyway, also keep in mind that a product's UV protection is no longer a debatable point if the formula it's in washes away. Tiefenpfleger has been tested to be highly resistant to washing therefore UV protection is sustained. You'll find that as time goes by, you will need Tiefen less and less. It actually treats the component not just dress it up.
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