not really sure how to describe them, they are a piece of trim made from the same sort of black rubber as XR3 spoilers for example, the fix the the rear end of the sills infront of the back wheels on MK3 XR3 Escorts as part of the bodykit they had as standard. From memory they go up the arch a little bit, but i could be confusing matters here!
No great shakes if you haven't, just that i wouldn't mind a pair if i came across some