This is the piece that turns a long, narrow piece of stitching into a proper draft stopper or bolster cushion: a cotton etamine back, cut and finished, with the zip already sewn along the long side. The zip lets you take the pad out whenever the cover needs washing.
Sew it to the embroidered front right sides together, leaving the zip open so you can turn the work through; press the embroidery from the back and trim the seam allowances before assembling. The pad and the front panel are not included: pair the back with a Vervaco front panel in the size given, or with your own piece of the same dimensions.