What are these pieces called, can I get them repop?

Did you all see the thread on moparts about revitalizing rubber parts?
SOLVED A/C box vacuum pots, rejuvenate rubber innards
I haven't tried to verify the info (yet) but it seemed reasonably well researched.

One product that seems pretty safe is RU-glyde. It used to be sold in small cans but now I've only seen it in 1 gal. containers. Mostly used to aid in tire mounting now.