New rubbers and sponges?

When you buy new rubber does it come with a sponge to put under it?  I'm not sure if you change the sponge underneath at all or not? im just confused on this.  if you do replace the sponge does it come when you buy new rubber or do you just look for table tennis paddle sponge, or something along the lines of that?

Hi Jake,

Yes almost all the rubbers come with sponge already attached. When you are removing your rubber take the rubber and the sponge off together.