First tune up, Spark Plug Tube seals??

So its time to do a tune up on the Scamp for the first time since i had it. Plugs, wires, cap, rotor, points etc. The guy at the store asked if i wanted spark plug tube seals too.

What the heck are they. I told him i didnt have a Australian 225 hemi. What are they and what do they do.

Kinda a embarassing question since i have been around mopars all my life, and never replaced them if i needed to.