The wide width for full circle or long bias dresses or skirts. 4-ply silk is one of our favorite. We use it for pants - Ms. FineFabrics Winter, and Transitional Spring and Fall Uniform - is made using 4-ply. She wears them daily. Washes and drys them in the machine. We also use 4-ply for dresses, tunics and tops. 4-ply is a staple in the luxury fashion collection of Peter Cohen. Drapes beautifully without cling and a subtle sheen.