Padeen wrote:

"Take your bottle of Armorall to the nearest trash can and deposit it.
It's worthless junk that damages more materials than it preserves,
including your car."

can be said for 303 as well. I've found that the only use 303 has is to
force the use of more 303; very handy if you sell 303 but just another
consumer-targeted fraud. I've had my present drytop since 2000, have used
nothing on it, never washed it, store it in -50 deg. and expect to replace
the worn-out fabric (G-tx) before the gaskets.

I really disagree.

It's easy to see and feel the difference in suppleness after applying 303
to latex gaskets. The latex absorbs a certain amount of 303, causing it to
stretch better and slide more easily over your head and hands.

I agree that 303 is probably useless on anything but latex. Years ago
there was a magazine advertisement showing two PFDs, one treated with 303
and the other not treated, with the latter falling apart from UV damage.
This was supposedly from one treatment! I tried it and my PFD is faded
and the fabric is starting to fray, so I think the advertisement was BS.