It is not silk. It is polyester.
There is no indication on any of the 5 itmes that it is silk. I'm silk obsessed and bought it out of curiosity, because I wanted to see if it was silk for such price. The simple test indicates that it is not silk. Just take a fiber that sticks out and light it with match. Polyester melts and silk doesn't.
If you really want to buy silk this is not a brand to buy from, because they don't sell silk. But if you are not picky and, for the price fo 5 pieces, it is not bad even for polyester. Victoria's secret charges much more for their polyester pajamas.