The basics Firmly packed tailor's/dressmaker's ham for molding darts, curved seams and sleeve caps. The benefits Press as you sew for a professional finish. The uses Use plaid side (65% cotton/35% polyester) for woolens, synthetic blends & fabrics requiring low to medium temperatures. Use cotton side (100% cotton) for cotton, linen & fabrics requiring medium to high temperatures. The bottom line This tool is a must have for garment sewers.