Porch awning

Si Jo Tom and Ems

Just picked and used for the first time a Bradcott porch awning, canvas type. Came with a rather odd bit. The wheel cover and skirt are obvious enough its the padded cushion thing with a black plastic figure 8 bit running its lenght? its about 5 or so feet long, about 3inches wide and an inch thick. Its padded, The awning when fitted runs up the rear channel and across the top half way along the van, the loose side then fits tight against the van side. No idea what the cushion bit with the black thing is for. I bought it off a non vanner so no history or instructions. Any ideas? Cheers.