I had some but i took them off. I got them at radio shack for like 2 bucks. I'm sure they were not the right ones, but i was using them on my front 6 and 1/2s. I am not sure which HU you have, but I took all of the bass out of my interior speakers and only have them playing highs. I read out of the car audio cookbook that they weren't needed, so i tried them, didnt like them and got rid of them. It felt like i was missing something. I mean you could turn you bass and everything up and the speakers would not move, but as the book said, if you properly tune your system they are not needed.
If yo must have them, BB sells them, but I'm sure a flea market near you sells them as well. I suggested BB because the ones i saw were specific for different sized speakers.