The wiper seal is the base attachment for the "D" seal. My wiper seal is attached to the side of the RV body with screws. Some of the screw heads had rusted and broken off leaving the wiper loose in areas. I added new and more screws to reattach the wiper. Then replaced the slide-on "D" seal to the wiper base. Be sure to seal the upper edge of the D seal with Geocel sealant.
i purchased the D seal in a 50 foot roll from Dyer RV on line. The top D seal on all three of my slides had turned to goo in sections and needed replacement. The side D seals on the slides are okay