PolyPro Performance embroidery backing was designed to reduce puckering when embroidering microfiber performance shirts and moisture wicking materials with excessive stretch in the fabric. When using PolyPro, we recommend the following for best results: Hoop or float a piece of Medium Soft Tearaway backing next to the machine table. Do not stretch the garment when hooping and keep hoop level (do not recess inner hoop). PolyPro Performance is a heat-sensitive product. It is recommended that garments hang to dry. If placed in a clothes dryer, use a short time on a cool setting. Ironing is not recommended. If ironing is required, iron on low setting from right side of fabric only.