Jasen Betts wrote in a message to Roy J. Tellason:

 RJT> I don't think that the seals are available as a separate part.
 RJT> (Considering doing that on my car.

 JB> You should be able to get a kit from the dealer or a brake
 JB> specialist containing only the rubber bits for your brakes.

I would have thought so too,  but these days the pricing it such that it's
easier/cheaper to just replace the whole caliper,  master cylinder,  or
whatever.  Same thing with wheel cylinders...

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