A zip guard does as the name suggests, guards against a blouse or undergarment getting trapped in the zip when closing. It also serves to neaten a waistband underlap providing a professional finish.
After inserting the zip, cut fabric the same length as the zip, including zip tape and 2″ (5 cm) wide. Curve the bottom left hand corner and overlock the edges.
Place zip guard behind zip matching the length.
With zip guard underneath, pin in place in order to pin the zip guard to the right back seam allowance.
After checking position from right side, machine stitch in place through zip tape and seam allowance only (two layers!) using zipper foot.