21% synthetic material sounds excessive, but who knows.
Not to hijack the thread, but this reminds me of a Brioni trunk show I stumbled upon at a Neiman Marcus and just tried on some jackets. I found a red cashmere jacket, and I thought, "What the hell, why not try on a red jacket to see if I like how the color looks on me." I don't recall the exact percentages, but the fabric tag listed wool, silk, and cashmere, using these abbreviations.
A huckster -- not sure if he was with Brioni or Neiman Marcus -- then jumped on me for the sale. I wasn't 100% sure that WS stood for cashmere, so I asked him if he knew what it stood for. He tried to convince me that WS meant wool and silk. I figured that was wrong, since both were already stated separately. I really didn't feel like pressing the point, so I just put the jacket back and thanked him for his time.
He could have used this listing.