the plastic in the center of the vinyl albums

mypeacewillsetmefree

that little circular disc that comes with the x mas vinyl in the center, what is it called? what does it mean? does it symbolize anything that doesn't concern pj.
i ask because it will be my first tattoo. i have a vinyl window decal of it on my car; i love it. i get compliments/questions from people about it. the fact that only those who are into pj are aware of it. love it. just need some help. its one thing to put it on a vehicle, an entirely other thing to ink it on my back. thanks in advance.