Even though both of these clip-in sets are good for fine hair and super discreet they still have a few variations that set them apart. The Classic Full Head is a traditional clip in with a lace, sewn seam and only weighs 130 grams, its perfect for adding volume to thin hair. The Seamless has a stronger silicone seam and weighs from 150-190 grams, its good for adding both length and volume to thin or average thickness hair thanks to the double drawn thicker ends.