They' re used to dissipate static. They are usually made of black rubber, with metal fibres woven into the middle. They are bolted onto the frame, and drag on the ground, as you drive. I would expect that you could get them at an auto parts store. The ones I' ve seen look like flat black rubber, about an inch or inch and a half wide, 8-10 inches long, about an 1/8 inch thick.