What do I search for?

[250-R-250]

I am trying to find a Rubber block of some sort. I need this so that I can make some spacers and bushings. Problem is I cant find it on ebay. What should I type into the search bar? Is there a special name?
Also, is there any other material that I should consider that would be good at this application? Derlin?Delrin? something like that.

[Ghost-Rider]

Well ... i moved to middle nowhere over summer so this could jsut be some redneck comin out in me but uh... them big rectanglar rubber blocks ( like 2-4 inchs high like 1-2 foot long ) made outa like ruber you usem for cleanin the disk sanders you could cut them but they would wear away if after a lil but .... yea thats probly jsut sum redneck outburst :macho