They attach to the back of a canopy frame by using ball bungees that loop through each grommet hole and around the frame pole. All back wall tarps are made of heavy-duty 12 poly material that is waterproof, rot-proof, and UV-resistant. When ordering a full replacement carport kit, you will receive one rear panel and one zippered front panel. Do you need a size that is not on our website? Give us a call at 541-951-2861, we have sizes in our warehouse that are not listed. READ LESS